Hello R-users, thanks to Brian Ripley, who guided me through this process, the "tcltk" package is now working and hence the "Rcmdr" package as well. The secrets were to first rebuild the Tcl and Tk packages from the sources files, making sure the same C compiler was used as the one used in subsequent steps to build R and enabling 64bit support. Prof. Ripley reported getting warnings, regarding 64bit support, when using the gcc compiler. configure: warning: 64bit mode not supported with GCC on SunOS-5.8 configure: warning: 64bit support being disabled -- don't know magic for this platform I used the Forte cc compiler and didn't get these warnings. I wanted a 64bit built of R under Solaris 8 and setted the compilation flags as specified in the "R Installation and Admin." manual. Then it was just a matter of running configure with the "--with-tcl-config=" and " --with-tk-config=" options pointing to the files "tclConfig.sh" and "tkConfig.sh" respectively. Once R built successfully installing the "Rcmdr" and it's required libraries was a piece of cake. I still have to learn R, particularly how it is different from Splus, which I have been using for years. Thanks again to all who helped and a special thank you to Brian Ripley, G?rald Jean Analyste-conseil (statistiques), Actuariat t?lephone : (418) 835-4900 poste (7639) t?lecopieur : (418) 835-6657 courrier ?lectronique: gerald.jean at spgdag.ca "In God we trust all others must bring data" W. Edwards Deming