I have set G4VIS... environmental variables but visualization does not appear to be enabled. This might be because you set the environment variables *after* already compiling. The environment variables control C-pre-processor macros of the same name and therefore influence what code gets compiled. It is suggested to proceed with the following manual procedure to correct the current installation: Configure the environment according to the installation making sure to -unset- the G4WORKDIR environment variable, if set. Verify and eventually set the environment variables of the visualization module [name] concerned (setenv or export both G4VIS_BUILD_[name]_DRIVER and G4VIS_USE_[name] variables according to the UNIX shell used), and then proceed as follows: cd $G4INSTALL/source/visualization gmake clean gmake cd $G4INSTALL/source/interfaces gmake clean gmake cd $G4INSTALL/source gmake libmap setenv G4WORKDIR [your working directory] (or export) cd [your application directory] gmake clean gmake