diff --git a/lib/Client/GitlabClient.php b/lib/Client/GitlabClient.php
index 734deba..4c58e46 100644
--- a/lib/Client/GitlabClient.php
+++ b/lib/Client/GitlabClient.php
@@ -10,6 +10,10 @@
 
 namespace Gitlab\Client;
 
+use Gitlab\Entity\Comment;
+use Gitlab\Entity\CommentCollection;
+use Gitlab\Entity\MergeRequest;
+
 interface GitlabClient
 {
     /**
@@ -25,4 +29,52 @@ interface GitlabClient
      * @return \Gitlab\Entity\MergeRequest[]
      */
     public function listMergeRequests($projectId, $state = null, $orderBy = null, $sort = null, $page = null, $perPage = null);
+
+    /**
+     * Shows information about the merge request including its files and changes.
+     * @param string $projectId
+     * @param string $mergeRequestId
+     * @return MergeRequest
+     */
+    public function getMergeRequest($projectId, $mergeRequestId);
+
+    /**
+     * Creates a new merge request.
+     * @param MergeRequest $mergeRequest
+     * @return MergeRequest
+     */
+    public function createMergeRequest(MergeRequest $mergeRequest);
+
+    /**
+     * Updates an existing merge request. You can change branches, title, or even close the MR.
+     * @param MergeRequest $mergeRequest
+     * @return MergeRequest
+     */
+    public function updateMergeRequest(MergeRequest $mergeRequest);
+
+    /**
+     * Merge changes submitted with MR using this API.
+     * @param string $projectId
+     * @param int $mergeRequestId
+     * @param string|null $commitMessage Custom merge commit message
+     * @return MergeRequest
+     */
+    public function acceptMergeRequest($projectId, $mergeRequestId, $commitMessage = null);
+
+    /**
+     * Adds a comment to a merge request.
+     * @param string $projectId
+     * @param int $mergeRequestId
+     * @param string $note Text of the comment
+     * @return Comment
+     */
+    public function createMergeRequestComment($projectId, $mergeRequestId, $note);
+
+    /**
+     * Gets all the comments associated with a merge request.
+     * @param string $projectId
+     * @param int $mergeRequestId
+     * @return CommentCollection
+     */
+    public function getMergeRequestComments($projectId, $mergeRequestId);
 }
diff --git a/lib/Client/GitlabGuzzleClient.php b/lib/Client/GitlabGuzzleClient.php
index 16eb8ce..5158a61 100644
--- a/lib/Client/GitlabGuzzleClient.php
+++ b/lib/Client/GitlabGuzzleClient.php
@@ -32,7 +32,7 @@
  * @see GitlabGuzzleClient::acceptMergeRequest
  * @method array getMergeRequestChanges($parameters)
  * @method MergeRequest createMergeRequestComment($parameters)
- * @method CommentCollection listMergeRequestComments($parameters)
+ * @method CommentCollection getMergeRequestComments($parameters)
  *
  * Commits API
  * @see https://github.com/gitlabhq/gitlabhq/blob/v7.7.0/doc/api/commits.md
@@ -154,9 +154,9 @@ public function listMergeRequests(array $parameters)
      * @param array $parameters
      * @return MergeRequest
      */
-    public function createMergeRequest(array $parameters)
+    public function getMergeRequest(array $parameters)
     {
-        $command = $this->getCommand('createMergeRequest', $parameters);
+        $command = $this->getCommand('getMergeRequest', $parameters);
 
         /** @var MergeRequest $mergeRequest */
         $mergeRequest = $this->execute($command);
@@ -169,9 +169,9 @@ public function createMergeRequest(array $parameters)
      * @param array $parameters
      * @return MergeRequest
      */
-    public function getMergeRequest(array $parameters)
+    public function createMergeRequest(array $parameters)
     {
-        $command = $this->getCommand('getMergeRequest', $parameters);
+        $command = $this->getCommand('createMergeRequest', $parameters);
 
         /** @var MergeRequest $mergeRequest */
         $mergeRequest = $this->execute($command);
diff --git a/lib/Client/HttpGitlabClient.php b/lib/Client/HttpGitlabClient.php
index 23a4d0d..64572d7 100644
--- a/lib/Client/HttpGitlabClient.php
+++ b/lib/Client/HttpGitlabClient.php
@@ -10,6 +10,8 @@
 
 namespace Gitlab\Client;
 
+use Gitlab\Entity\MergeRequest;
+
 class HttpGitlabClient implements GitlabClient
 {
     private $client;
@@ -30,4 +32,63 @@ public function listMergeRequests($projectId, $state = null, $orderBy = null, $s
             'per_page'   => $perPage,
         ]));
     }
+
+    public function getMergeRequest($projectId, $mergeRequestId)
+    {
+        return $this->client->getMergeRequest(array_filter([
+            'project_id' => $projectId,
+            'merge_request_id' => $mergeRequestId,
+        ]));
+    }
+
+    public function createMergeRequest(MergeRequest $mergeRequest)
+    {
+        return $this->client->createMergeRequest(array_filter([
+            'project_id'    => $mergeRequest->project,
+            'source_branch' => $mergeRequest->sourceBranch,
+            'target_branch' => $mergeRequest->targetBranch,
+            'title'         => $mergeRequest->title,
+            'description'   => $mergeRequest->description,
+            'assignee_id'   => isset($mergeRequest->assignee) ? $mergeRequest->assignee->id : null,
+        ]));
+    }
+
+    public function updateMergeRequest(MergeRequest $mergeRequest)
+    {
+        return $this->client->updateMergeRequest(array_filter([
+            'project_id'       => $mergeRequest->project,
+            'merge_request_id' => $mergeRequest->id,
+            'source_branch'    => $mergeRequest->sourceBranch,
+            'target_branch'    => $mergeRequest->targetBranch,
+            'title'            => $mergeRequest->title,
+            'description'      => $mergeRequest->description,
+            'assignee_id'      => isset($mergeRequest->assignee) ? $mergeRequest->assignee->id : null,
+        ]));
+    }
+
+    public function acceptMergeRequest($projectId, $mergeRequestId, $commitMessage = null)
+    {
+        return $this->client->acceptMergeRequest(array_filter([
+            'project_id'           => $projectId,
+            'merge_request_id'     => $mergeRequestId,
+            'merge_commit_message' => $commitMessage,
+        ]));
+    }
+
+    public function createMergeRequestComment($projectId, $mergeRequestId, $note)
+    {
+        return $this->client->createMergeRequestComment(array_filter([
+            'project_id'       => $projectId,
+            'merge_request_id' => $mergeRequestId,
+            'note'             => $note,
+        ]));
+    }
+
+    public function getMergeRequestComments($projectId, $mergeRequestId)
+    {
+        return $this->client->getMergeRequestComments(array_filter([
+            'project_id'       => $projectId,
+            'merge_request_id' => $mergeRequestId,
+        ]));
+    }
 }
diff --git a/lib/Client/MockGitlabClient.php b/lib/Client/MockGitlabClient.php
index c86c431..29194c5 100644
--- a/lib/Client/MockGitlabClient.php
+++ b/lib/Client/MockGitlabClient.php
@@ -10,10 +10,52 @@
 
 namespace Gitlab\Client;
 
+use Gitlab\Entity\Comment;
+use Gitlab\Entity\CommentCollection;
+use Gitlab\Entity\MergeRequest;
+
 class MockGitlabClient implements GitlabClient
 {
     public function listMergeRequests($projectId, $state = null, $orderBy = null, $sort = null, $page = null, $perPage = null)
     {
         return [];
     }
+
+    public function getMergeRequest($projectId, $mergeRequestId)
+    {
+        return $this->createMockMergeRequest($projectId, $mergeRequestId);
+    }
+
+    public function createMergeRequest(MergeRequest $mergeRequest)
+    {
+        return $mergeRequest;
+    }
+
+    public function updateMergeRequest(MergeRequest $mergeRequest)
+    {
+        return $mergeRequest;
+    }
+
+    public function acceptMergeRequest($projectId, $mergeRequestId, $commitMessage = null)
+    {
+        return $this->createMockMergeRequest($projectId, $mergeRequestId);
+    }
+
+    public function createMergeRequestComment($projectId, $mergeRequestId, $note)
+    {
+        return new Comment($note);
+    }
+
+    public function getMergeRequestComments($projectId, $mergeRequestId)
+    {
+        return new CommentCollection();
+    }
+
+    private function createMockMergeRequest($projectId, $mergeRequestId)
+    {
+        $mergeRequest = new MergeRequest($projectId, "Mock merge request #$mergeRequestId");
+        $mergeRequest->id = $mergeRequestId;
+
+        return $mergeRequest;
+    }
 }
diff --git a/lib/Client/ServiceDescription/merge_requests_api.yml b/lib/Client/ServiceDescription/merge_requests_api.yml
index 43730e6..c6b1bb2 100644
--- a/lib/Client/ServiceDescription/merge_requests_api.yml
+++ b/lib/Client/ServiceDescription/merge_requests_api.yml
@@ -207,7 +207,7 @@ operations:
                 type: string
                 location: postField
 
-    listMergeRequestComments:
+    getMergeRequestComments:
         extends: paginatedOperation
         summary: Adds a comment to a merge request.
         responseClass: Gitlab\Entity\CommentCollection
diff --git a/lib/Entity/MergeRequest.php b/lib/Entity/MergeRequest.php
index c818f6a..bd6d5c1 100644
--- a/lib/Entity/MergeRequest.php
+++ b/lib/Entity/MergeRequest.php
@@ -81,6 +81,19 @@ public static function fromArray(array $data)
         return $mergeRequest;
     }
 
+    /**
+     * MergeRequest constructor.
+     * @param string $project
+     * @param string $title
+     * @param int|null $id
+     */
+    public function __construct($project = '', $title = '', $id = null)
+    {
+        $this->project = $project;
+        $this->title = $title;
+        $this->id = $id;
+    }
+
     public function __toString()
     {
         return sprintf('Merge request: %s (%s)', $this->title, $this->getCrossProjectReference());
diff --git a/tests/Client/HttpGitlabClientTest.php b/tests/Client/HttpGitlabClientTest.php
index 436918e..d9b078f 100644
--- a/tests/Client/HttpGitlabClientTest.php
+++ b/tests/Client/HttpGitlabClientTest.php
@@ -10,9 +10,13 @@
 
 namespace Client;
 
+use Gitlab\Client\GitlabClient;
 use Gitlab\Client\GitlabGuzzleClient;
 use Gitlab\Client\HttpGitlabClient;
+use Gitlab\Entity\Comment;
+use Gitlab\Entity\CommentCollection;
 use Gitlab\Entity\MergeRequest;
+use Gitlab\Entity\User;
 use Mockery;
 use Mockery\MockInterface;
 use PHPUnit_Framework_TestCase;
@@ -22,7 +26,7 @@ class HttpGitlabClientTest extends PHPUnit_Framework_TestCase
     /** @var GitlabGuzzleClient|MockInterface */
     private $guzzle;
 
-    /** @var HttpGitlabClient */
+    /** @var GitlabClient */
     private $client;
 
     protected function setUp()
@@ -34,9 +38,9 @@ protected function setUp()
     public function testListMergeRequests()
     {
         $expectedResult = [
-            new MergeRequest('fgrosse/example', 42, 'MR No. 42'),
-            new MergeRequest('fgrosse/example', 43, "cthulhu r'lyeh fhtagn"),
-            new MergeRequest('fgrosse/example', 44, 'Hello Gitlab World'),
+            new MergeRequest('fgrosse/example', 'MR No. 42'),
+            new MergeRequest('fgrosse/example', "cthulhu r'lyeh fhtagn"),
+            new MergeRequest('fgrosse/example', 'Hello Gitlab World'),
         ];
 
         $this->guzzle->shouldReceive('listMergeRequests')->once()->with(Mockery::on(function ($params) {
@@ -54,4 +58,129 @@ public function testListMergeRequests()
         $actualResult = $this->client->listMergeRequests('fgrosse/example', 'opened', 'created_at', 'desc', 42, 3);
         $this->assertEquals($expectedResult, $actualResult);
     }
+
+    public function testGetMergeRequest()
+    {
+        $expectedResult = new MergeRequest('fgrosse/example', 'MR No. 42', 42);
+
+        $this->guzzle->shouldReceive('getMergeRequest')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id'       => 'fgrosse/example',
+                'merge_request_id' => 42,
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->getMergeRequest('fgrosse/example', 42);
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
+    public function testCreateMergeRequest()
+    {
+        $assignee = new User();
+        $assignee->id = 1;
+        $mergeRequest = new MergeRequest('fgrosse/example', 'MR No. 42');
+        $mergeRequest->sourceBranch = 'develop';
+        $mergeRequest->targetBranch = 'master';
+        $mergeRequest->assignee = $assignee;
+        $mergeRequest->description = 'My description';
+        $expectedResult = clone $mergeRequest;
+        $expectedResult->id = 42;
+
+        $this->guzzle->shouldReceive('createMergeRequest')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id' => 'fgrosse/example',
+                'source_branch' => 'develop',
+                'target_branch' => 'master',
+                'title' => 'MR No. 42',
+                'assignee_id' => 1,
+                'description' => 'My description',
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->createMergeRequest($mergeRequest);
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
+    public function testUpdateMergeRequest()
+    {
+        $assignee = new User();
+        $assignee->id = 1;
+        $mergeRequest = new MergeRequest('fgrosse/example', 'MR No. 42', 42);
+        $mergeRequest->sourceBranch = 'develop';
+        $mergeRequest->targetBranch = 'master';
+        $mergeRequest->assignee = $assignee;
+        $mergeRequest->description = 'My description';
+        $expectedResult = clone $mergeRequest;
+
+        $this->guzzle->shouldReceive('updateMergeRequest')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id' => 'fgrosse/example',
+                'merge_request_id' => 42,
+                'source_branch' => 'develop',
+                'target_branch' => 'master',
+                'title' => 'MR No. 42',
+                'assignee_id' => 1,
+                'description' => 'My description',
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->updateMergeRequest($mergeRequest);
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
+    public function testAcceptMergeRequest()
+    {
+        $expectedResult = new MergeRequest('fgrosse/example', 'MR No. 42', 42);
+        $expectedResult->sourceBranch = 'develop';
+        $expectedResult->targetBranch = 'master';
+        $expectedResult->description = 'My description';
+
+        $this->guzzle->shouldReceive('acceptMergeRequest')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id' => 'fgrosse/example',
+                'merge_request_id' => 42,
+                'merge_commit_message' => 'Okey dokey',
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->acceptMergeRequest('fgrosse/example', 42, 'Okey dokey');
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
+    public function testCreateMergeRequestComment()
+    {
+        $expectedResult = new Comment('Nice work joe!');
+        $this->guzzle->shouldReceive('createMergeRequestComment')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id' => 'fgrosse/example',
+                'merge_request_id' => 42,
+                'note' => 'Nice work joe!',
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->createMergeRequestComment('fgrosse/example', 42, 'Nice work joe!');
+        $this->assertEquals($expectedResult, $actualResult);
+    }
+
+    public function testGetMergeRequestComments()
+    {
+        $expectedResult = new CommentCollection();
+        $expectedResult[] = new Comment('Foo');
+        $expectedResult[] = new Comment('Bar');
+        $this->guzzle->shouldReceive('getMergeRequestComments')->once()->with(Mockery::on(function ($params) {
+            $this->assertEquals([
+                'project_id' => 'fgrosse/example',
+                'merge_request_id' => 42,
+            ], $params);
+            return true;
+        }))->andReturn($expectedResult);
+
+        $actualResult = $this->client->getMergeRequestComments('fgrosse/example', 42);
+        $this->assertEquals($expectedResult, $actualResult);
+    }
 }
diff --git a/tests/Client/MergeRequestsAPITest.php b/tests/Client/MergeRequestsAPITest.php
index 9407db5..fbdbb4d 100644
--- a/tests/Client/MergeRequestsAPITest.php
+++ b/tests/Client/MergeRequestsAPITest.php
@@ -179,12 +179,12 @@ public function testCreateMergeRequestComment()
         $this->assertInstanceOf(Comment::class, $comment);
     }
 
-    public function testListMergeRequestComments()
+    public function testGetMergeRequestComments()
     {
         $this->setMockResponse(__DIR__.'/fixtures/merge_requests/list_merge_request_comments.http');
         $projectId = 'fgrosse/example-project';
         $mergeRequestId = 42;
-        $comments = $this->client->listMergeRequestComments([
+        $comments = $this->client->getMergeRequestComments([
             'project_id'       => $projectId,
             'merge_request_id' => $mergeRequestId,
             'page'             => 3,