anonymous wrote : In other words what I am saying is that all hibernate validators work as you describe EXCEPT @NotNull/@Length(min=1). OK. After some more trials, I found that with no required="true" and: - @NotNull, the null value is accepted! - any other hibernate validation which assumes a non null string, as @Length(min=1), a exception is generated and uncaught. For exemple with a null input : - "^\\w*$" will be fine - "^\\w+$" will throw an uncaught exception Petemuir, thanks for help. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3981755#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...