diff --git a/documentation/ref-manual/ref-classes.xml b/documentation/ref-manual/ref-classes.xml
index 8184c1c5a9..3103604542 100644
--- a/documentation/ref-manual/ref-classes.xml
+++ b/documentation/ref-manual/ref-classes.xml
@@ -2686,6 +2686,17 @@
     </para>
 </section>
 
+<section id='ref-classes-setuptools3'>
+    <title><filename>setuptools3.bbclass</filename></title>
+
+    <para>
+        The <filename>setuptools3</filename> class supports Python
+        version 3.x extensions that use setuptools3-based build systems.
+        If your recipe uses these build systems, the recipe needs to
+        inherit the <filename>setuptools3</filename> class.
+    </para>
+</section>
+
 <section id='ref-classes-sip'>
     <title><filename>sip.bbclass</filename></title>