Well, I am using document/literal wrapped for my wsdl file, and what I have found so far is that mtom only works if the parameter type of the method is DataHandler. For example, this works: @WebMethod @RequestWrapper(localName = "sendOctet", targetNamespace = "http://xxx.com/webservice/mtom/", className = "com.xxx.webservice.mtom.SendOctet") @ResponseWrapper(localName = "sendOctetResponse", targetNamespace = "http://xxx.com/stat/webservice/mtom/", className = "com.xxx.webservice.mtom.SendOctetResponse") public void sendOctet( @WebParam(name = "octet", targetNamespace = "") DataHandler octet, But if I pass something like List, or another holder bean that contains a DataHandler field, mtom does not work anymore, and the message is send inline. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4170124#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...