diff --git a/reference/classobj/functions/is-subclass-of.xml b/reference/classobj/functions/is-subclass-of.xml
index 945d06b059..37479aec03 100644
--- a/reference/classobj/functions/is-subclass-of.xml
+++ b/reference/classobj/functions/is-subclass-of.xml
@@ -76,6 +76,13 @@
         Added <parameter>allow_string</parameter> parameter
        </entry>
       </row>
+      <row>
+       <entry>5.3.7</entry>
+       <entry>
+        Added support for <parameter>class_name</parameter> to work with
+        intrefaces 
+       </entry>
+      </row>
       <row>
        <entry>5.0.3</entry>
        <entry>
@@ -141,6 +148,57 @@ if (is_subclass_of('WidgetFactory_Child', 'WidgetFactory')) {
 yes, $WFC is a subclass of WidgetFactory
 no, $WF is not a subclass of WidgetFactory
 yes, WidgetFactory_Child is a subclass of WidgetFactory
+]]>
+    </screen>
+   </example>
+  </para>
+  <para>
+   <example>
+    <title><function>is_subclass_of</function> using interface example</title>
+    <programlisting role="php">
+<![CDATA[
+<?php
+// Define the Interface
+interface MyInterface
+{
+  public function MyFunction();
+}
+
+// Define the class implementation of the interface
+class MyClass implements MyInterface
+{
+  public function MyFunction()
+  {
+    return "MyClass Implements MyInterface!";
+  }
+}
+
+// Instantiate the object
+$my_object = new MyClass;
+
+// Works since 5.3.7
+
+// Test using the object instance of the class
+if (is_subclass_of($my_object, 'MyInterface')) {
+  echo "Yes, \$my_object is a subclass of MyInterface\n";
+} else {
+  echo "No, \$my_object is not a subclass of MyInterface\n";
+}
+
+// Test using a string of the class name
+if (is_subclass_of('MyClass', 'MyInterface')) {
+  echo "Yes, MyClass is a subclass of MyInterface\n";
+} else {
+  echo "No, MyClass is not a subclass of MyInterface\n";
+}
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+Yes, $my_object is a subclass of MyInterface
+Yes, MyClass is a subclass of MyInterface
 ]]>
     </screen>
    </example>