Dear all I haven been trying to install MPICH-3.1 for a month, but always failed. I use Absoft Fortran and configured the MPICH with the following command ./configure --prefix=/opt/mpich2-install F77=$ABSOFT/bin/af90 \ FC=$ABSOFT/bin/af90 --with-pm=mpd I got the following error message: configure: error: The selected Fortran 90 compiler /Applications/Absoft10.2/bin/af90 does not work with the selected Fortran 77 compiler /Applications/Absoft10.2/bin/af90. Use the environment variables FC and F77 respectively to select compatible Fortran compilers. The check here tests to see if a main program compiled with the Fortran 90 compiler can link with a subroutine compiled with the Fortran 77 compiler. I also tried the configure line in the Readme file of MPICH-3.1 and the following one, ./configure --prefix=/opt/mpich2-install F77=$ABSOFT/bin/af77 \ FC=$ABSOFT/bin/af90 --with-pm=mp All gave me the similar error message. Attached please find the config.log file. Any help/suggestions will be greatly appreciated! Best Yan