Output from Perl 5.8.0 -V is Summary of my perl5 (revision 5 version 8 subversion 0) configuration: Platform: osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread usethreads=undef use5005threads=undef useithreads=define usemultiplicity=define which basically says that useithreads is defined. But I also get for 5.6, the same Summary of my perl5 (revision 5 version 6 subversion 0) configuration: Platform: osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread usethreads=undef use5005threads=undef useithreads=define usemultiplicity=define And my perl test program does not work with 5.6 as I dont have the thread module. Another question is does use Thread and use threads same? What is the difference between them? thanks, -sureshr