I looked over your code at it looks like it shoud be OK to me. I Tried to compile it with my VC 71 system using boost 1.3 (cvs HEAD) and I got an error at the following line: class ABC : public IA, public IB, public IC \BoostHead\libs\serialization\test\test_zmisc.cpp(85) : fatal error C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 2701) Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information which looks to me to be an artifact of the test system. I'll look some more if I can get the chance. Robert Ramey "Michel Pineau" <mpineau1963@yahoo.com> wrote in message news:478215.90532.qm@web53310.mail.re2.yahoo.com... Hello, I'm trying to serialize many boost::shared_ptr to the same object but through different base classes. When I look at the boost::shared_ptr for the base classes they are not properly set. I created a simple example that show my problem. The test program output is: