Thanks for both of you guys...Now i have another small problem i hope.. When i'm trying to run de exe file after the program was finally succesfull compiled it give me this error "MPI_COMM_RANK : Null communicator"...I found out this may because the older version of the file mpif.h that come with the program above ( pi.f and mpif.h could be found at this addres ftp://info.mcs.anl.gov/pub/mpi/usingmpi-1st/examples/simplempi/ ) is incompatible with the librarie that comes with the program MPICH ( http://www-unix.mcs.anl.gov/mpi/mpich1/mpich-nt/ )...If i take the new version of mpif.h file that come MPIH program, it give the following error during the compilation "Error: This symbol has multiply declared DEC$ ATTRIBUTES DLLIMPORT attribute. [MPIPRIV] mpif.h"...What should i do next!!1..Thank you