Which version of JBoss AS are you using? I assume you are using JBoss WS 1.2, and that you are using wsrunclient to run the client. Most likely, there is a missing jar from the classpath (I found that the wsdl4j.jar was missing, I'm using JBoss AS 5.0 beta 2 (or actually, the svn trunk from Monday). Anyway, the missing file is in jboss-saaj.jar, or at least that is where I found it. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4025998#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...