diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index b599c48eb7db..d69b90131ffd 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -165,6 +165,10 @@ function enumBody(context: Object, node: Object) {
     context.print(member, node);
     context.newline();
   }
+  if (node.hasUnknownMembers) {
+    context.token("...");
+    context.newline();
+  }
   context.dedent();
   context.token("}");
 }
diff --git a/packages/babel-generator/test/fixtures/flow/enum-declaration/input.js b/packages/babel-generator/test/fixtures/flow/enum-declaration/input.js
index f59944f78e18..ca45dfef54b1 100644
--- a/packages/babel-generator/test/fixtures/flow/enum-declaration/input.js
+++ b/packages/babel-generator/test/fixtures/flow/enum-declaration/input.js
@@ -34,3 +34,9 @@ enum E of symbol {
   A,
   B,
 }
+
+enum E {
+  A,
+  B,
+  ...
+}
diff --git a/packages/babel-generator/test/fixtures/flow/enum-declaration/output.js b/packages/babel-generator/test/fixtures/flow/enum-declaration/output.js
index f59944f78e18..ca993e1d2944 100644
--- a/packages/babel-generator/test/fixtures/flow/enum-declaration/output.js
+++ b/packages/babel-generator/test/fixtures/flow/enum-declaration/output.js
@@ -34,3 +34,8 @@ enum E of symbol {
   A,
   B,
 }
+enum E {
+  A,
+  B,
+  ...
+}
diff --git a/packages/babel-parser/src/plugins/flow.js b/packages/babel-parser/src/plugins/flow.js
index 26ddfeaae787..6740dd286add 100644
--- a/packages/babel-parser/src/plugins/flow.js
+++ b/packages/babel-parser/src/plugins/flow.js
@@ -3252,10 +3252,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       enumName: string,
       explicitType: EnumExplicitType,
     }): {|
-      booleanMembers: Array<N.Node>,
-      numberMembers: Array<N.Node>,
-      stringMembers: Array<N.Node>,
-      defaultedMembers: Array<N.Node>,
+      members: {|
+        booleanMembers: Array<N.Node>,
+        numberMembers: Array<N.Node>,
+        stringMembers: Array<N.Node>,
+        defaultedMembers: Array<N.Node>,
+      |},
+      hasUnknownMembers: boolean,
     |} {
       const seenNames = new Set();
       const members = {
@@ -3264,7 +3267,12 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         stringMembers: [],
         defaultedMembers: [],
       };
+      let hasUnknownMembers = false;
       while (!this.match(tt.braceR)) {
+        if (this.eat(tt.ellipsis)) {
+          hasUnknownMembers = true;
+          break;
+        }
         const memberNode = this.startNode();
         const { id, init } = this.flowEnumMemberRaw();
         const memberName = id.name;
@@ -3341,7 +3349,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
           this.expect(tt.comma);
         }
       }
-      return members;
+      return { members, hasUnknownMembers };
     }
 
     flowEnumStringMembers(
@@ -3408,7 +3416,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     flowEnumBody(node: N.Node, { enumName, nameLoc }): N.Node {
       const explicitType = this.flowEnumParseExplicitType({ enumName });
       this.expect(tt.braceL);
-      const members = this.flowEnumMembers({ enumName, explicitType });
+      const { members, hasUnknownMembers } = this.flowEnumMembers({
+        enumName,
+        explicitType,
+      });
+      node.hasUnknownMembers = hasUnknownMembers;
 
       switch (explicitType) {
         case "boolean":
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-explicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-explicit/output.json
index 02b996288588..c34b19b78a3e 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-explicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-explicit/output.json
@@ -48,7 +48,8 @@
                 "value": false
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-implicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-implicit/output.json
index 1cde4241aa48..c17beff73c00 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-implicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-implicit/output.json
@@ -19,6 +19,7 @@
           "type": "EnumBooleanBody",
           "start":7,"end":35,"loc":{"start":{"line":1,"column":7},"end":{"line":4,"column":1}},
           "explicitType": false,
+          "hasUnknownMembers": false,
           "members": [
             {
               "type": "EnumBooleanMember",
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-explicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-explicit/output.json
index 9cd2d5701c55..c8d39bd0832c 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-explicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-explicit/output.json
@@ -22,7 +22,8 @@
           "type": "EnumBooleanBody",
           "start":7,"end":26,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-implicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-implicit/output.json
index ef24cd6ca0fd..a50af0f91c04 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-implicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/boolean-member-not-initialized-implicit/output.json
@@ -22,6 +22,7 @@
           "type": "EnumBooleanBody",
           "start":7,"end":27,"loc":{"start":{"line":1,"column":7},"end":{"line":4,"column":1}},
           "explicitType": false,
+          "hasUnknownMembers": false,
           "members": [
             {
               "type": "EnumBooleanMember",
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/duplicate-member-name/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/duplicate-member-name/output.json
index 5ebbed1e950a..0a31c3040a72 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/duplicate-member-name/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/duplicate-member-name/output.json
@@ -41,7 +41,8 @@
                 "name": "A"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/empty/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/empty/output.json
index df6b983d915f..8251d5bbd5f9 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/empty/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/empty/output.json
@@ -19,7 +19,8 @@
           "type": "EnumStringBody",
           "start":7,"end":10,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":10}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/enum-name/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/enum-name/output.json
index 758f952645c5..ae5d55919942 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/enum-name/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/enum-name/output.json
@@ -19,7 +19,8 @@
           "type": "EnumStringBody",
           "start":10,"end":13,"loc":{"start":{"line":1,"column":10},"end":{"line":2,"column":1}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/export/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/export/output.json
index f5ddd9661e42..30a5ede01a69 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/export/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/export/output.json
@@ -25,7 +25,8 @@
             "type": "EnumStringBody",
             "start":14,"end":16,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":16}},
             "explicitType": false,
-            "members": []
+            "members": [],
+            "hasUnknownMembers": false
           }
         }
       },
@@ -44,7 +45,8 @@
             "type": "EnumStringBody",
             "start":40,"end":42,"loc":{"start":{"line":3,"column":22},"end":{"line":3,"column":24}},
             "explicitType": false,
-            "members": []
+            "members": [],
+            "hasUnknownMembers": false
           }
         }
       }
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-majority-defaulted/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-majority-defaulted/output.json
index e63c726b3b70..d39e36c96dd2 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-majority-defaulted/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-majority-defaulted/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":7,"end":29,"loc":{"start":{"line":1,"column":7},"end":{"line":5,"column":1}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-mixed-initializers/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-mixed-initializers/output.json
index 8f536f701906..17e38f263e66 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-mixed-initializers/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/inconsistent-member-values-mixed-initializers/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":7,"end":31,"loc":{"start":{"line":1,"column":7},"end":{"line":4,"column":1}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-explicit-type-identifier/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-explicit-type-identifier/output.json
index bdd2f9ac8fb1..02a9f0f0b04e 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-explicit-type-identifier/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-explicit-type-identifier/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":7,"end":17,"loc":{"start":{"line":1,"column":7},"end":{"line":2,"column":1}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-boolean-explicit-string/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-boolean-explicit-string/output.json
index 0c9f36244f81..9e16c209ebc8 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-boolean-explicit-string/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-boolean-explicit-string/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":7,"end":32,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-literal-explicit-symbol/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-literal-explicit-symbol/output.json
index cc53bdf91782..169c12667f22 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-literal-explicit-symbol/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-literal-explicit-symbol/output.json
@@ -21,7 +21,8 @@
         "body": {
           "type": "EnumSymbolBody",
           "start":7,"end":29,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-boolean/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-boolean/output.json
index 2e86e933c0d5..14bbdfbda955 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-boolean/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-boolean/output.json
@@ -22,7 +22,8 @@
           "type": "EnumBooleanBody",
           "start":7,"end":30,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-string/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-string/output.json
index 2d654faa00d2..c496f854cb46 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-string/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-number-explicit-string/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":7,"end":29,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-boolean/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-boolean/output.json
index 0d7f98f68eb8..3a7df84a7a47 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-boolean/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-boolean/output.json
@@ -22,7 +22,8 @@
           "type": "EnumBooleanBody",
           "start":7,"end":33,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-number/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-number/output.json
index b55c6b5b9d41..8a9c7b3bd378 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-number/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-initializer-string-explicit-number/output.json
@@ -22,7 +22,8 @@
           "type": "EnumNumberBody",
           "start":7,"end":32,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-name/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-name/output.json
index 9fe35c22085d..dc53fd5d5a79 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-name/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/invalid-member-name/output.json
@@ -42,7 +42,8 @@
                 "name": "bar"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/no-trailing-comma/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/no-trailing-comma/output.json
index 2d409165d994..5f6412acfdf1 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/no-trailing-comma/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/no-trailing-comma/output.json
@@ -29,7 +29,8 @@
                 "name": "A"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-explicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-explicit/output.json
index 7422817d7443..eb54b373d2bf 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-explicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-explicit/output.json
@@ -56,7 +56,8 @@
                 "value": 2
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-implicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-implicit/output.json
index 56cc5c9ace8a..bb4166ab487b 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-implicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-implicit/output.json
@@ -19,6 +19,7 @@
           "type": "EnumNumberBody",
           "start":7,"end":28,"loc":{"start":{"line":1,"column":7},"end":{"line":4,"column":1}},
           "explicitType": false,
+          "hasUnknownMembers": false,
           "members": [
             {
               "type": "EnumNumberMember",
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-explicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-explicit/output.json
index da174b55f384..fb8576d1afaa 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-explicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-explicit/output.json
@@ -22,7 +22,8 @@
           "type": "EnumNumberBody",
           "start":7,"end":25,"loc":{"start":{"line":1,"column":7},"end":{"line":3,"column":1}},
           "explicitType": true,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-implicit/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-implicit/output.json
index baf3a7cb99ec..61135052b682 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-implicit/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/number-member-not-initialized-implicit/output.json
@@ -22,6 +22,7 @@
           "type": "EnumNumberBody",
           "start":7,"end":24,"loc":{"start":{"line":1,"column":7},"end":{"line":4,"column":1}},
           "explicitType": false,
+          "hasUnknownMembers": false,
           "members": [
             {
               "type": "EnumNumberMember",
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/reserved-word-enum-name/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/reserved-word-enum-name/output.json
index 2eb913529f69..a48c8cad045b 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/reserved-word-enum-name/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/reserved-word-enum-name/output.json
@@ -22,7 +22,8 @@
           "type": "EnumStringBody",
           "start":11,"end":14,"loc":{"start":{"line":1,"column":11},"end":{"line":2,"column":1}},
           "explicitType": false,
-          "members": []
+          "members": [],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-defaulted/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-defaulted/output.json
index 00c64b6bad97..9946ca0ad2c7 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-defaulted/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-defaulted/output.json
@@ -38,7 +38,8 @@
                 "name": "B"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-initialized/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-initialized/output.json
index b2d881c84b94..e9c04de11f28 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-initialized/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-explicit-initialized/output.json
@@ -56,7 +56,8 @@
                 "value": "b"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-defaulted/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-defaulted/output.json
index ca27f1e722d6..e3a939805c54 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-defaulted/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-defaulted/output.json
@@ -38,7 +38,8 @@
                 "name": "B"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-initialized/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-initialized/output.json
index d6f642c684e7..b7c04a9e0121 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-initialized/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-implicit-initialized/output.json
@@ -56,7 +56,8 @@
                 "value": "b"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-defaulted/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-defaulted/output.json
index b2f08dfac888..7f5906cc2ff0 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-defaulted/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-defaulted/output.json
@@ -41,7 +41,8 @@
                 "name": "C"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-initialized/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-initialized/output.json
index 01371ce1c56f..d57bcebfb9f8 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-initialized/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/string-member-inconsistently-initialized-majority-initialized/output.json
@@ -59,7 +59,8 @@
                 "value": "c"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/symbol/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/symbol/output.json
index 4497d3a6d362..91a4161a67d4 100644
--- a/packages/babel-parser/test/fixtures/flow/enum-declaration/symbol/output.json
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/symbol/output.json
@@ -37,7 +37,8 @@
                 "name": "B"
               }
             }
-          ]
+          ],
+          "hasUnknownMembers": false
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/input.js b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/input.js
new file mode 100644
index 000000000000..7cf551a186bd
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/input.js
@@ -0,0 +1,3 @@
+enum E {
+  ...,
+}
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/options.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/options.json
new file mode 100644
index 000000000000..f2b07fdae549
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members-invalid/options.json
@@ -0,0 +1,11 @@
+{
+  "plugins": [
+    [
+      "flow",
+      {
+        "enums": true
+      }
+    ]
+  ],
+  "throws": "Unexpected token, expected \"}\" (2:5)"
+}
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/input.js b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/input.js
new file mode 100644
index 000000000000..87a82d84a080
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/input.js
@@ -0,0 +1,5 @@
+enum E {
+  A,
+  B,
+  ...
+}
diff --git a/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/output.json b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/output.json
new file mode 100644
index 000000000000..b681e62d1045
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/enum-declaration/unknown-members/output.json
@@ -0,0 +1,48 @@
+{
+  "type": "File",
+  "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":5,"column":1}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":5,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "EnumDeclaration",
+        "start":0,"end":26,"loc":{"start":{"line":1,"column":0},"end":{"line":5,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":6,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":6},"identifierName":"E"},
+          "name": "E"
+        },
+        "body": {
+          "type": "EnumStringBody",
+          "start":7,"end":26,"loc":{"start":{"line":1,"column":7},"end":{"line":5,"column":1}},
+          "explicitType": false,
+          "members": [
+            {
+              "type": "EnumDefaultedMember",
+              "start":11,"end":12,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":3}},
+              "id": {
+                "type": "Identifier",
+                "start":11,"end":12,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":3},"identifierName":"A"},
+                "name": "A"
+              }
+            },
+            {
+              "type": "EnumDefaultedMember",
+              "start":16,"end":17,"loc":{"start":{"line":3,"column":2},"end":{"line":3,"column":3}},
+              "id": {
+                "type": "Identifier",
+                "start":16,"end":17,"loc":{"start":{"line":3,"column":2},"end":{"line":3,"column":3},"identifierName":"B"},
+                "name": "B"
+              }
+            }
+          ],
+          "hasUnknownMembers": true
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-types/src/definitions/flow.js b/packages/babel-types/src/definitions/flow.js
index 182b6fec6e4e..ea7ab39ccef2 100644
--- a/packages/babel-types/src/definitions/flow.js
+++ b/packages/babel-types/src/definitions/flow.js
@@ -491,6 +491,7 @@ defineType("EnumBooleanBody", {
   fields: {
     explicit: validate(assertValueType("boolean")),
     members: validateArrayOfType("EnumBooleanMember"),
+    hasUnknownMembers: validate(assertValueType("boolean")),
   },
 });
 
@@ -500,6 +501,7 @@ defineType("EnumNumberBody", {
   fields: {
     explicit: validate(assertValueType("boolean")),
     members: validateArrayOfType("EnumNumberMember"),
+    hasUnknownMembers: validate(assertValueType("boolean")),
   },
 });
 
@@ -509,6 +511,7 @@ defineType("EnumStringBody", {
   fields: {
     explicit: validate(assertValueType("boolean")),
     members: validateArrayOfType(["EnumStringMember", "EnumDefaultedMember"]),
+    hasUnknownMembers: validate(assertValueType("boolean")),
   },
 });
 
@@ -517,6 +520,7 @@ defineType("EnumSymbolBody", {
   visitor: ["members"],
   fields: {
     members: validateArrayOfType("EnumDefaultedMember"),
+    hasUnknownMembers: validate(assertValueType("boolean")),
   },
 });