Hello, using the attached files (executing testexc,bash) I got different results between toplevel and compiled: ===================================================== Testcase A exception A of int * int let _ = raise ( A(3,4) ) Exception: A (3, 4). Fatal error: exception Exca.A(3, 4) Fatal error: exception Exca.A(3, 4) Testcase B exception B of (int*int) let _ = raise ( B(3,4) ) Exception: B (3, 4). Fatal error: exception Excb.B(_) Fatal error: exception Excb.B(_) ===================================================== So just adding parantheses in a definition of an exception yields in these differing results, with not-shown exception-values. IMHO looks like a case for the bugtracker... OCaml version is 4.02.1 Ciao, Oliver