Tomas, Try something like this
typedef int (__stdcall *TheCallbackType) (int); DECLARE_INTERFACE_(umIDataSink, IUnknown) { STDMETHOD(SetCallback) (THIS_ TheCallbackType Callback) PURE; }; and on the managed side delegate int TheCallBackType(int i); But why are you using a function pointer rather than an interface for callbacks? Mattias === Mattias Sjögren [EMAIL PROTECTED] You can read messages from the DOTNET archive, unsubscribe from DOTNET, or subscribe to other DevelopMentor lists at http://discuss.develop.com.