diff --git a/google/cloud/documentai/v1beta3/document_io.proto b/google/cloud/documentai/v1beta3/document_io.proto
index e10bea84087d0..e41458e0a241a 100644
--- a/google/cloud/documentai/v1beta3/document_io.proto
+++ b/google/cloud/documentai/v1beta3/document_io.proto
@@ -16,6 +16,8 @@ syntax = "proto3";
 
 package google.cloud.documentai.v1beta3;
 
+import "google/protobuf/field_mask.proto";
+
 option csharp_namespace = "Google.Cloud.DocumentAI.V1Beta3";
 option go_package = "google.golang.org/genproto/googleapis/cloud/documentai/v1beta3;documentai";
 option java_multiple_files = true;
@@ -74,6 +76,11 @@ message DocumentOutputConfig {
   message GcsOutputConfig {
     // The Cloud Storage uri (a directory) of the output.
     string gcs_uri = 1;
+
+    // Specifies which fields to include in the output documents.
+    // Only supports top level document and pages field so it must be in the
+    // form of `{document_field_name}` or `pages.{page_field_name}`.
+    google.protobuf.FieldMask field_mask = 2;
   }
 
   // The destination of the results.