diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 9284465eefc28..f9c87e949615d 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -31785,6 +31785,9 @@ namespace ts {
                         return grammarErrorAtPos(node, node.end - 1, ";".length, Diagnostics._0_expected, "{");
                     }
                 }
+                else if (isClassLike(node.parent) && isStringLiteral(node.name) && node.name.text === "constructor" && (!compilerOptions.target || compilerOptions.target < ScriptTarget.ES5)) {
+                    return grammarErrorOnNode(node.name, Diagnostics.Quoted_constructors_have_previously_been_interpreted_as_methods_which_is_incorrect_In_TypeScript_3_6_they_will_be_correctly_parsed_as_constructors_In_the_meantime_consider_using_constructor_to_write_a_constructor_or_constructor_to_write_a_method);
+                }
                 if (checkGrammarForGenerator(node)) {
                     return true;
                 }
@@ -32103,6 +32106,9 @@ namespace ts {
 
         function checkGrammarProperty(node: PropertyDeclaration | PropertySignature) {
             if (isClassLike(node.parent)) {
+                if (isStringLiteral(node.name) && node.name.text === "constructor") {
+                    return grammarErrorOnNode(node.name, Diagnostics.Classes_may_not_have_a_field_named_constructor);
+                }
                 if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_class_property_declaration_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) {
                     return true;
                 }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 8342a4dd6c4d5..af3ecad79a669 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -4965,5 +4965,13 @@
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer." :{
         "category": "Error",
         "code": 18004
+    },
+    "Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '[\"constructor\"]()' to write a method.": {
+        "category": "Error",
+        "code": 18005
+    },
+    "Classes may not have a field named 'constructor'.": {
+        "category": "Error",
+        "code": 18006
     }
 }
diff --git a/tests/baselines/reference/convertKeywordsYes.errors.txt b/tests/baselines/reference/convertKeywordsYes.errors.txt
index 7218e1fd12c66..e142e6de03d7f 100644
--- a/tests/baselines/reference/convertKeywordsYes.errors.txt
+++ b/tests/baselines/reference/convertKeywordsYes.errors.txt
@@ -1,3 +1,4 @@
+tests/cases/compiler/convertKeywordsYes.ts(175,12): error TS18006: Classes may not have a field named 'constructor'.
 tests/cases/compiler/convertKeywordsYes.ts(292,11): error TS1213: Identifier expected. 'implements' is a reserved word in strict mode. Class definitions are automatically in strict mode.
 tests/cases/compiler/convertKeywordsYes.ts(293,11): error TS1213: Identifier expected. 'interface' is a reserved word in strict mode. Class definitions are automatically in strict mode.
 tests/cases/compiler/convertKeywordsYes.ts(294,11): error TS1213: Identifier expected. 'let' is a reserved word in strict mode. Class definitions are automatically in strict mode.
@@ -9,7 +10,7 @@ tests/cases/compiler/convertKeywordsYes.ts(301,11): error TS1213: Identifier exp
 tests/cases/compiler/convertKeywordsYes.ts(303,11): error TS1213: Identifier expected. 'yield' is a reserved word in strict mode. Class definitions are automatically in strict mode.
 
 
-==== tests/cases/compiler/convertKeywordsYes.ts (9 errors) ====
+==== tests/cases/compiler/convertKeywordsYes.ts (10 errors) ====
     // reserved ES5 future in strict mode
     
     var constructor = 0;
@@ -185,6 +186,8 @@ tests/cases/compiler/convertKeywordsYes.ts(303,11): error TS1213: Identifier exp
     
     class bigClass {
         public "constructor" = 0;
+               ~~~~~~~~~~~~~
+!!! error TS18006: Classes may not have a field named 'constructor'.
         public any = 0;
         public boolean = 0;
         public implements = 0;
diff --git a/tests/baselines/reference/propertyNamedConstructor.errors.txt b/tests/baselines/reference/propertyNamedConstructor.errors.txt
new file mode 100644
index 0000000000000..e275131a50c36
--- /dev/null
+++ b/tests/baselines/reference/propertyNamedConstructor.errors.txt
@@ -0,0 +1,14 @@
+tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts(2,3): error TS18006: Classes may not have a field named 'constructor'.
+
+
+==== tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts (1 errors) ====
+    class X1 {
+      "constructor" = 3; // Error
+      ~~~~~~~~~~~~~
+!!! error TS18006: Classes may not have a field named 'constructor'.
+    }
+    
+    class X2 {
+      ["constructor"] = 3;
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/propertyNamedConstructor.js b/tests/baselines/reference/propertyNamedConstructor.js
new file mode 100644
index 0000000000000..8b7752ab6d558
--- /dev/null
+++ b/tests/baselines/reference/propertyNamedConstructor.js
@@ -0,0 +1,23 @@
+//// [propertyNamedConstructor.ts]
+class X1 {
+  "constructor" = 3; // Error
+}
+
+class X2 {
+  ["constructor"] = 3;
+}
+
+
+//// [propertyNamedConstructor.js]
+var X1 = /** @class */ (function () {
+    function X1() {
+        this["constructor"] = 3; // Error
+    }
+    return X1;
+}());
+var X2 = /** @class */ (function () {
+    function X2() {
+        this["constructor"] = 3;
+    }
+    return X2;
+}());
diff --git a/tests/baselines/reference/propertyNamedConstructor.symbols b/tests/baselines/reference/propertyNamedConstructor.symbols
new file mode 100644
index 0000000000000..b8a028d8444b8
--- /dev/null
+++ b/tests/baselines/reference/propertyNamedConstructor.symbols
@@ -0,0 +1,16 @@
+=== tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts ===
+class X1 {
+>X1 : Symbol(X1, Decl(propertyNamedConstructor.ts, 0, 0))
+
+  "constructor" = 3; // Error
+>"constructor" : Symbol(X1["constructor"], Decl(propertyNamedConstructor.ts, 0, 10))
+}
+
+class X2 {
+>X2 : Symbol(X2, Decl(propertyNamedConstructor.ts, 2, 1))
+
+  ["constructor"] = 3;
+>["constructor"] : Symbol(X2["constructor"], Decl(propertyNamedConstructor.ts, 4, 10))
+>"constructor" : Symbol(X2["constructor"], Decl(propertyNamedConstructor.ts, 4, 10))
+}
+
diff --git a/tests/baselines/reference/propertyNamedConstructor.types b/tests/baselines/reference/propertyNamedConstructor.types
new file mode 100644
index 0000000000000..6b90f31e917ad
--- /dev/null
+++ b/tests/baselines/reference/propertyNamedConstructor.types
@@ -0,0 +1,18 @@
+=== tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts ===
+class X1 {
+>X1 : X1
+
+  "constructor" = 3; // Error
+>"constructor" : number
+>3 : 3
+}
+
+class X2 {
+>X2 : X2
+
+  ["constructor"] = 3;
+>["constructor"] : number
+>"constructor" : "constructor"
+>3 : 3
+}
+
diff --git a/tests/baselines/reference/quotedConstructors.errors.txt b/tests/baselines/reference/quotedConstructors.errors.txt
new file mode 100644
index 0000000000000..9e70452ff4062
--- /dev/null
+++ b/tests/baselines/reference/quotedConstructors.errors.txt
@@ -0,0 +1,30 @@
+tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts(2,5): error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts(6,5): error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts(14,5): error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+
+
+==== tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts (3 errors) ====
+    class C {
+        "constructor"() {} // Error in 3.5
+        ~~~~~~~~~~~~~
+!!! error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+    }
+    
+    class D {
+        'constructor'() {} // Error in 3.5
+        ~~~~~~~~~~~~~
+!!! error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+    }
+    
+    class E {
+        ['constructor']() {}
+    }
+    
+    new class {
+        "constructor"() {} // Error in 3.5
+        ~~~~~~~~~~~~~
+!!! error TS18005: Quoted constructors have previously been interpreted as methods, which is incorrect. In TypeScript 3.6, they will be correctly parsed as constructors. In the meantime, consider using 'constructor()' to write a constructor, or '["constructor"]()' to write a method.
+    };
+    
+    var o = { "constructor"() {} };
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/quotedConstructors.js b/tests/baselines/reference/quotedConstructors.js
new file mode 100644
index 0000000000000..c9a662e6af526
--- /dev/null
+++ b/tests/baselines/reference/quotedConstructors.js
@@ -0,0 +1,46 @@
+//// [quotedConstructors.ts]
+class C {
+    "constructor"() {} // Error in 3.5
+}
+
+class D {
+    'constructor'() {} // Error in 3.5
+}
+
+class E {
+    ['constructor']() {}
+}
+
+new class {
+    "constructor"() {} // Error in 3.5
+};
+
+var o = { "constructor"() {} };
+
+
+//// [quotedConstructors.js]
+var C = /** @class */ (function () {
+    function C() {
+    }
+    C.prototype["constructor"] = function () { }; // Error in 3.5
+    return C;
+}());
+var D = /** @class */ (function () {
+    function D() {
+    }
+    D.prototype['constructor'] = function () { }; // Error in 3.5
+    return D;
+}());
+var E = /** @class */ (function () {
+    function E() {
+    }
+    E.prototype['constructor'] = function () { };
+    return E;
+}());
+new /** @class */ (function () {
+    function class_1() {
+    }
+    class_1.prototype["constructor"] = function () { }; // Error in 3.5
+    return class_1;
+}());
+var o = { "constructor": function () { } };
diff --git a/tests/baselines/reference/quotedConstructors.symbols b/tests/baselines/reference/quotedConstructors.symbols
new file mode 100644
index 0000000000000..be68e48484754
--- /dev/null
+++ b/tests/baselines/reference/quotedConstructors.symbols
@@ -0,0 +1,33 @@
+=== tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts ===
+class C {
+>C : Symbol(C, Decl(quotedConstructors.ts, 0, 0))
+
+    "constructor"() {} // Error in 3.5
+>"constructor" : Symbol(C["constructor"], Decl(quotedConstructors.ts, 0, 9))
+}
+
+class D {
+>D : Symbol(D, Decl(quotedConstructors.ts, 2, 1))
+
+    'constructor'() {} // Error in 3.5
+>'constructor' : Symbol(D['constructor'], Decl(quotedConstructors.ts, 4, 9))
+}
+
+class E {
+>E : Symbol(E, Decl(quotedConstructors.ts, 6, 1))
+
+    ['constructor']() {}
+>['constructor'] : Symbol(E['constructor'], Decl(quotedConstructors.ts, 8, 9))
+>'constructor' : Symbol(E['constructor'], Decl(quotedConstructors.ts, 8, 9))
+}
+
+new class {
+    "constructor"() {} // Error in 3.5
+>"constructor" : Symbol((Anonymous class)["constructor"], Decl(quotedConstructors.ts, 12, 11))
+
+};
+
+var o = { "constructor"() {} };
+>o : Symbol(o, Decl(quotedConstructors.ts, 16, 3))
+>"constructor" : Symbol("constructor", Decl(quotedConstructors.ts, 16, 9))
+
diff --git a/tests/baselines/reference/quotedConstructors.types b/tests/baselines/reference/quotedConstructors.types
new file mode 100644
index 0000000000000..907a2152a80ac
--- /dev/null
+++ b/tests/baselines/reference/quotedConstructors.types
@@ -0,0 +1,37 @@
+=== tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts ===
+class C {
+>C : C
+
+    "constructor"() {} // Error in 3.5
+>"constructor" : () => void
+}
+
+class D {
+>D : D
+
+    'constructor'() {} // Error in 3.5
+>'constructor' : () => void
+}
+
+class E {
+>E : E
+
+    ['constructor']() {}
+>['constructor'] : () => void
+>'constructor' : "constructor"
+}
+
+new class {
+>new class {    "constructor"() {} // Error in 3.5} : (Anonymous class)
+>class {    "constructor"() {} // Error in 3.5} : typeof (Anonymous class)
+
+    "constructor"() {} // Error in 3.5
+>"constructor" : () => void
+
+};
+
+var o = { "constructor"() {} };
+>o : { "constructor"(): void; }
+>{ "constructor"() {} } : { "constructor"(): void; }
+>"constructor" : () => void
+
diff --git a/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts b/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts
new file mode 100644
index 0000000000000..3ab45c72810cd
--- /dev/null
+++ b/tests/cases/conformance/classes/constructorDeclarations/quotedConstructors.ts
@@ -0,0 +1,17 @@
+class C {
+    "constructor"() {} // Error in 3.5
+}
+
+class D {
+    'constructor'() {} // Error in 3.5
+}
+
+class E {
+    ['constructor']() {}
+}
+
+new class {
+    "constructor"() {} // Error in 3.5
+};
+
+var o = { "constructor"() {} };
diff --git a/tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts b/tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts
new file mode 100644
index 0000000000000..49c53a9894f05
--- /dev/null
+++ b/tests/cases/conformance/classes/propertyMemberDeclarations/propertyNamedConstructor.ts
@@ -0,0 +1,7 @@
+class X1 {
+  "constructor" = 3; // Error
+}
+
+class X2 {
+  ["constructor"] = 3;
+}