diff --git a/blog/lib/dynamo.js b/blog/lib/dynamo.js
index ace75e9..8a384c8 100644
--- a/blog/lib/dynamo.js
+++ b/blog/lib/dynamo.js
@@ -26,6 +26,31 @@ export function createPost(post) {
   });
 }
 
+export function createComment(comment) {
+  return new Promise(function(resolve, reject) {
+    var params = {
+      TableName: commentsTable,
+      Item: comment
+    };
+
+    docClient.get({
+      TableName: postsTable,
+      Key: {
+        id: comment.postId
+      },
+      AttributesToGet: [ "id" ]
+    }, function(err, data) {
+      if (err) return reject(err);
+      if(!data.Item) return reject(new Error(`Post with id: ${comment.postId} does not exist`));
+
+      docClient.put(params, function(err, data) {
+        if (err) return reject(err);
+        return resolve(comment);
+      });
+    })
+  });
+}
+
 export function getPosts() {
   return new Promise(function(resolve, reject) {
     var params = {
@@ -85,15 +110,14 @@ export function getAuthors() {
   });
 }
 
-export function getComments() {
+export function getComments(postId) {
   return new Promise(function(resolve, reject) {
     var params = {
       TableName: commentsTable,
-      AttributesToGet: [
-        'id',
-        'content',
-        'author'
-      ]
+      FilterExpression : 'postId = :postId',
+      ExpressionAttributeValues : {
+        ':postId' : postId
+      }
     };
 
     docClient.scan(params, function(err, data) {
diff --git a/blog/lib/schema.js b/blog/lib/schema.js
index e6b5e51..faf274f 100644
--- a/blog/lib/schema.js
+++ b/blog/lib/schema.js
@@ -1,3 +1,5 @@
+import uuid from 'uuid';
+
 import {
   GraphQLObjectType,
   GraphQLSchema,
@@ -10,7 +12,7 @@ import {
   GraphQLLimitedString
 } from 'graphql-custom-types';
 
-import { getPosts, getAuthor, getAuthors, getComments, createPost } from './dynamo';
+import { getPosts, getAuthor, getAuthors, getComments, createPost, createComment } from './dynamo';
 
 const Author = new GraphQLObjectType({
   name: "Author",
@@ -52,7 +54,7 @@ const Post = new GraphQLObjectType({
     comments: {
       type: new GraphQLList(Comment),
       resolve: function(post) {
-        return getComments();
+        return getComments(post.id);
       }
     }
   })
@@ -92,11 +94,30 @@ const Query = new GraphQLObjectType({
 const Mutuation = new GraphQLObjectType({
   name: 'BlogMutations',
   fields: {
+    createComment: {
+      type: Comment,
+      description: "Create blog comment",
+      args: {
+        id: {
+          type: GraphQLString,
+          defaultValue: uuid.v4()
+        },
+        postId: {type: new GraphQLNonNull(GraphQLString)},
+        content: {type: new GraphQLNonNull(GraphQLString)},
+        author: {type: new GraphQLNonNull(GraphQLString), description: "Id of the author"}
+      },
+      resolve: function(source, args) {
+        return createComment(args);
+      }
+    },
     createPost: {
       type: Post,
       description: "Create blog post",
       args: {
-        id: {type: new GraphQLNonNull(GraphQLString)},
+        id: {
+          type: GraphQLString,
+          defaultValue: uuid.v4()
+        },
         title: {type: new GraphQLLimitedString(10, 30)},
         bodyContent: {type: new GraphQLNonNull(GraphQLString)},
         author: {type: new GraphQLNonNull(GraphQLString), description: "Id of the author"}
diff --git a/blog/package.json b/blog/package.json
index f7dccb1..0d0c3c8 100644
--- a/blog/package.json
+++ b/blog/package.json
@@ -15,6 +15,7 @@
     "bluebird": "^3.1.1",
     "graphql": "^0.4.14",
     "graphql-custom-types": "^0.2.0",
-    "serverless-helpers-js": "~0.0.3"
+    "serverless-helpers-js": "~0.0.3",
+    "uuid": "2.0.2"
   }
 }