Hi, Perhaps someone can provide a solution to what seems to be a problem with installation of mpich. I installed ifort (intel) and mpich (via port install), compile a basic test program mpif90 -I/usr/local/include -o tst tst.f (here "I/usr/local/include" is included to find mpif-common.h), PROGRAM mpitest integer ierr,my_rank,nm_prcs include "mpif-common.h" call MPI_INIT(ierr) write(*,*)MPI_INTEGER,MPI_REAL,MPI_DOUBLE_PRECISION call MPI_COMM_RANK(MPI_COMM_WORLD,my_rank,ierr) call MPI_COMM_SIZE(MPI_COMM_WORLD,nm_prcs,ierr) write(*,*)'MPI:',my_rank,nm_prcs,ierr call MPI_FINALIZE(ierr) end and do mpirun -np 2 ./tst. The result is 7 13 17 MPI: 0 1 0 7 13 17 MPI: 0 1 0 It shows that nm_prcs = 1 and both processes show the same my_rank = 0, even though ierr =0. The initialization in mpirun seem to fail, to assign a proper process count 2. Any ideas on what's amiss? Many thanks, Henry.