diff --git a/src/wp-includes/class-wp-comment-query.php b/src/wp-includes/class-wp-comment-query.php
index f4bb7f6c60..01048e6a3f 100644
--- a/src/wp-includes/class-wp-comment-query.php
+++ b/src/wp-includes/class-wp-comment-query.php
@@ -92,7 +92,8 @@ class WP_Comment_Query {
 	 *
 	 * Sets up the comment query, based on the query vars passed.
 	 *
-	 * @since  4.2.0
+	 * @since 4.2.0
+	 * @since 4.4.0 `$parent__in` and `$parent__not_in` were added.
 	 * @access public
 	 *
 	 * @param string|array $query {
@@ -136,6 +137,8 @@ class WP_Comment_Query {
 	 *     @type string       $order               How to order retrieved comments. Accepts 'ASC', 'DESC'.
 	 *                                             Default: 'DESC'.
 	 *     @type int          $parent              Parent ID of comment to retrieve children of. Default empty.
+	 *     @type array        $parent__in          Array of parent IDs of comments to retrieve children for. Default empty.
+	 *     @type array        $parent__not_in      Array of parent IDs of comments *not* to retrieve children for. Default empty.
 	 *     @type array        $post_author__in     Array of author IDs to retrieve comments for. Default empty.
 	 *     @type array        $post_author__not_in Array of author IDs *not* to retrieve comments for. Default empty.
 	 *     @type int          $post_ID             Currently unused.
@@ -486,6 +489,16 @@ class WP_Comment_Query {
 			$where[] = "$wpdb->comments.comment_ID NOT IN ( " . implode( ',', wp_parse_id_list( $this->query_vars['comment__not_in'] ) ) . ' )';
 		}
 
+		// Parse comment parent IDs for an IN clause.
+		if ( ! empty( $this->query_vars['parent__in'] ) ) {
+			$where[] = 'comment_parent IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['parent__in'] ) ) . ' )';
+		}
+
+		// Parse comment parent IDs for a NOT IN clause.
+		if ( ! empty( $this->query_vars['parent__not_in'] ) ) {
+			$where[] = 'comment_parent NOT IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['parent__not_in'] ) ) . ' )';
+		}
+
 		// Parse comment post IDs for an IN clause.
 		if ( ! empty( $this->query_vars['post__in'] ) ) {
 			$where[] = 'comment_post_ID IN ( ' . implode( ',', wp_parse_id_list( $this->query_vars['post__in'] ) ) . ' )';
diff --git a/tests/phpunit/tests/comment/query.php b/tests/phpunit/tests/comment/query.php
index 420d8f2dad..7356541ef4 100644
--- a/tests/phpunit/tests/comment/query.php
+++ b/tests/phpunit/tests/comment/query.php
@@ -1737,4 +1737,104 @@ class Tests_Comment_Query extends WP_UnitTestCase {
 		$q->query_vars['meta_key'] = 'foo';
 		$q->query_vars['meta_value'] = 'bar';
 	}
+
+	/**
+	 * @ticket 33882
+	 */
+	public function test_parent__in() {
+		$c1 = $this->factory->comment->create( array( 'comment_post_ID' => $this->post_id, 'comment_approved' => '1' ) );
+		$c2 = $this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c1,
+		) );
+
+		$ids = new WP_Comment_Query( array(
+			'comment_post_ID' => $this->post_id,
+			'fields' => 'ids',
+			'parent__in' => array( $c1 )
+		) );
+
+		$this->assertEqualSets( array( $c2 ), $ids->comments );
+	}
+
+	/**
+	 * @ticket 33882
+	 */
+	public function test_parent__in_commas() {
+		$c1 = $this->factory->comment->create( array( 'comment_post_ID' => $this->post_id, 'comment_approved' => '1' ) );
+		$c2 = $this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1'
+		) );
+		$c3 = $this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c1,
+		) );
+		$c4 = $this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c2,
+		) );
+
+		$ids = new WP_Comment_Query( array(
+			'comment_post_ID' => $this->post_id,
+			'fields' => 'ids',
+			'parent__in' => "$c1,$c2"
+		) );
+
+		$this->assertEqualSets( array( $c3, $c4 ), $ids->comments );
+	}
+
+	/**
+	 * @ticket 33882
+	 */
+	public function test_parent__not_in() {
+		$c1 = $this->factory->comment->create( array( 'comment_post_ID' => $this->post_id, 'comment_approved' => '1' ) );
+
+		$this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c1,
+		) );
+
+		$ids = new WP_Comment_Query( array(
+			'comment_post_ID' => $this->post_id,
+			'fields' => 'ids',
+			'parent__not_in' => array( $c1 )
+		) );
+
+		$this->assertEqualSets( array( $c1 ), $ids->comments );
+	}
+
+	/**
+	 * @ticket 33882
+	 */
+	public function test_parent__not_in_commas() {
+		$c1 = $this->factory->comment->create( array( 'comment_post_ID' => $this->post_id, 'comment_approved' => '1' ) );
+		$c2 = $this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1'
+		) );
+
+		$this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c1,
+		) );
+		$this->factory->comment->create( array(
+			'comment_post_ID' => $this->post_id,
+			'comment_approved' => '1',
+			'comment_parent' => $c2,
+		) );
+
+		$ids = new WP_Comment_Query( array(
+			'comment_post_ID' => $this->post_id,
+			'fields' => 'ids',
+			'parent__not_in' => "$c1,$c2"
+		) );
+
+		$this->assertEqualSets( array( $c1, $c2 ), $ids->comments );
+	}
 }