There is a gotcha when you follow the install instructions and drop in jbossws-1.0.4.GA into jbossas-4.0.4.GA and it has to do with updating the jboss-xml-binding.jar library from jbossxb/1.0.0.CR7. The JBossAS contains a library called jbossall-client.jar which a client of the JbossWS should use according to the wiki: http://wiki.jboss.org/wiki/Wiki.jsp?page=JBWSFAQClientJars Using jar tvf on jbossall-client.jar it looks like it is built from several jar files, including an older version of jboss-xml-binding.jar . I had to add jboss-xml-binding.jar to my client's class path but I had to put it before jbossall-client.jar. I would prefer to use the individual jar files that are used to build jbossall-client.jar. Is it possible for someone to post that list here or in the Wiki???