diff --git a/relation.module b/relation.module
index 5972ad1..52a01de 100644
--- a/relation.module
+++ b/relation.module
@@ -722,7 +722,8 @@ function relation_save($relation) {
     return FALSE;
   }
   $transaction = db_transaction();
-  $relation->arity = count($relation->endpoints[LANGUAGE_NONE]);
+  $endpoints = field_get_items('relation', $relation, 'endpoints');
+  $relation->arity = count($endpoints);
   // use time() instead of REQUEST_TIME, because otherwise tests
   // RelationQuery::order() are impossible.
   $relation->changed = time();
@@ -743,11 +744,25 @@ function relation_save($relation) {
   call_user_func("field_attach_$op", 'relation', $relation);
   module_invoke_all('entity_' . $op, $relation, 'relation');
   module_invoke('rules', 'invoke_event', 'relation_' . $op, $relation);
-  drupal_static_reset('relation_get_related_entity');
+  relation_clear_related_entities_cache($endpoints);
+
   return $relation->rid;
 }
 
 /**
+ * Clear the cache for a set of endpoints.
+ *
+ * @param $endpoints
+ *   An array of endpoints, with entity_type and entity_id as keys.
+ */
+function relation_clear_related_entities_cache($endpoints) {
+  drupal_static_reset('relation_get_related_entity');
+  foreach ($endpoints as $endpoint) {
+    cache_clear_all('relation:' . $endpoint['entity_type'] . ':' .  $endpoint['entity_id'], 'cache', TRUE);
+  }
+}
+
+/**
  * Insert a new relation in the database.
  */
 function relation_insert($type, $endpoints) {
@@ -785,6 +800,8 @@ function relation_delete_multiple($rids) {
     db_delete('relation_revision')->condition('rid', $rid)->execute();
     module_invoke_all('entity_delete', $relation, 'relation');
     field_attach_delete('relation', $relation);
+    $endpoints = field_get_items('relation', $relation, 'endpoints');
+    relation_clear_related_entities_cache($endpoints);
   }
 }
 
@@ -877,6 +894,9 @@ function relation_get_related_entity($entity_type, $entity_id, $relation_type =
   if (isset($items[$cache_key])) {
     $entities = $items[$cache_key];
   }
+  else if ($cached = cache_get('relation:' . $cache_key)) {
+    $entities = $items[$cache_key];
+  }
   else {
     $query = relation_query($entity_type, $entity_id, $r_index);
     if ($relation_type) {
@@ -891,6 +911,7 @@ function relation_get_related_entity($entity_type, $entity_id, $relation_type =
     else {
       $entities = FALSE;
     }
+    cache_set('relation:' . $cache_key, $entities);
     $items[$cache_key] = $entities;
   }
 
diff --git a/tests/relation.test b/tests/relation.test
index 2bc6434..24d46cc 100644
--- a/tests/relation.test
+++ b/tests/relation.test
@@ -266,6 +266,14 @@ class RelationAPITestCase extends RelationTestCase {
     // From Parent to Child.
     $related = relation_get_related_entity('node', $this->node3->nid, $this->relation_types['directional']['relation_type'], 0);
     $this->assertEqual($this->node4->nid, $related->nid);
+
+    // Delete all relations related to node 4, then confirm that these can
+    // no longer be found as related entities.
+    $relations = relation_query('node', $this->node4->nid)->execute();
+    foreach ($relations as $relation) {
+      relation_delete($relation->rid);
+    }
+    $this->assertFalse(relation_get_related_entity('node', $this->node4->nid), 'The entity was not loaded after the relation was deleted.');
   }
 
   /**