If you got the SVN downloaded javassist.jar is in the lib/ directory - or dist/ after building the profiler. There is a small note in the documentation about the need to include javassist.jar in bin/ for EAP 4.x / JBoss AS 4.2 -- see "Core libraries". The documentation could be a lot better - the first task in that direction is the documentation environment scheduled currently for Beta4. If you could track down why the classes aren't being profiled it would be great -- maybe try inserting some System.out's in agent.ProfilerThreadImpl, agent.Agent and agent.Profiler. TIA ! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4195770#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...