diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf178da7cc4..e258faa5b4e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ### vNEXT
 
 * Fix apollo-server-core runQuery breaks async_hooks tracking [PR #733](https://github.com/apollographql/apollo-server/pull/733)
+* Don't validate if query is already an AST. [PR #839](https://github.com/apollographql/apollo-server/pull/839)
 
 ### v1.3.0
 
diff --git a/packages/apollo-server-core/src/runHttpQuery.ts b/packages/apollo-server-core/src/runHttpQuery.ts
index 780ca7f97c3..c9deba735cb 100644
--- a/packages/apollo-server-core/src/runHttpQuery.ts
+++ b/packages/apollo-server-core/src/runHttpQuery.ts
@@ -105,8 +105,10 @@ export async function runHttpQuery(
   const requests: Array<ExecutionResult> = requestPayload.map(requestParams => {
     try {
       let query = requestParams.query;
+      const isQueryString = typeof query === 'string';
+
       if (isGetRequest) {
-        if (typeof query === 'string') {
+        if (isQueryString) {
           // preparse the query incase of GET so we can assert the operation.
           query = parse(query);
         }
@@ -149,6 +151,7 @@ export async function runHttpQuery(
         query: query,
         variables: variables,
         context,
+        isQueryString,
         rootValue: optionsObject.rootValue,
         operationName: operationName,
         logFunction: optionsObject.logFunction,
diff --git a/packages/apollo-server-core/src/runQuery.ts b/packages/apollo-server-core/src/runQuery.ts
index 5a3e4736999..65b2ba63b1f 100644
--- a/packages/apollo-server-core/src/runQuery.ts
+++ b/packages/apollo-server-core/src/runQuery.ts
@@ -69,6 +69,7 @@ export interface QueryOptions {
   debug?: boolean;
   tracing?: boolean;
   cacheControl?: boolean;
+  isQueryString?: boolean;
 }
 
 function runQuery(options: QueryOptions): Promise<GraphQLResponse> {
@@ -165,15 +166,17 @@ function doRunQuery(options: QueryOptions): Promise<GraphQLResponse> {
     documentAST = options.query as DocumentNode;
   }
 
-  let rules = specifiedRules;
-  if (options.validationRules) {
-    rules = rules.concat(options.validationRules);
-  }
-  logFunction({ action: LogAction.validation, step: LogStep.start });
-  const validationErrors = validate(options.schema, documentAST, rules);
-  logFunction({ action: LogAction.validation, step: LogStep.end });
-  if (validationErrors.length) {
-    return Promise.resolve({ errors: format(validationErrors) });
+  if (options.isQueryString !== false) {
+    let rules = specifiedRules;
+    if (options.validationRules) {
+      rules = rules.concat(options.validationRules);
+    }
+    logFunction({ action: LogAction.validation, step: LogStep.start });
+    const validationErrors = validate(options.schema, documentAST, rules);
+    logFunction({ action: LogAction.validation, step: LogStep.end });
+    if (validationErrors.length) {
+      return Promise.resolve({ errors: format(validationErrors) });
+    }
   }
 
   if (extensionStack) {
diff --git a/packages/apollo-server-express/src/apolloServerHttp.test.ts b/packages/apollo-server-express/src/apolloServerHttp.test.ts
index 24c6ac89e4b..56e609c910a 100644
--- a/packages/apollo-server-express/src/apolloServerHttp.test.ts
+++ b/packages/apollo-server-express/src/apolloServerHttp.test.ts
@@ -37,7 +37,9 @@ import {
   GraphQLScalarType,
   GraphQLError,
   BREAK,
+  parse,
 } from 'graphql';
+import { LogAction } from 'apollo-server-core';
 
 const QueryRootType = new GraphQLObjectType({
   name: 'QueryRoot',
@@ -538,4 +540,40 @@ describe(`GraphQL-HTTP (apolloServer) tests for ${version} express`, () => {
       });
     });
   });
+
+  describe('Query is an AST', () => {
+    it('Do not validate if query is already an AST.', async () => {
+      const app = express();
+      let validationCalled = false;
+
+      app.use('/graphql', bodyParser.json());
+      app.use('/graphql', (req, res, next) => {
+        req.body.query = parse(req.body.query);
+
+        next();
+      });
+      app.use(
+        '/graphql',
+        graphqlExpress({
+          schema: TestSchema,
+          logFunction: ({ action }) => {
+            if (action == LogAction.validation) {
+              validationCalled = true;
+            }
+          },
+        }),
+      );
+
+      const response = await request(app)
+        .post('/graphql')
+        .send({
+          query: '{ test(who: "World") }',
+        });
+
+      expect(
+        validationCalled,
+        'Validation should not be called if query is already an AST',
+      ).to.equal(false);
+    });
+  });
 });