Hi I would like to add a new observation with the above mail. The problem is seen only in the Debug Mode. The first line in the that method ("assert(false);"), which enables debugging was commented out and its not throwing any more Exception and working fine. //Server side in VC++ STDMETHODIMP CServerObj ::CallServerMethod(int integer, tagStruct *pVal, VARIANT vt) { //assert(false); } But I don't know why it was happening. Regards, Diana.