The MPI (Message Passing Interface) is a standard communication library implemented on a large number of parallel computers. It is used for the development of portable parallel software. This paper presents, evaluates and compares the performance of the point-to-point and broadcast communication primitives of the MPI standard library on the Meiko CS-2 parallel machine. Furthermore, the paper proposes a benchmark model of MPI communications based on the size of messages exchanged and the number of involved processors. Finally, the MPI performance results on the CS-2 are compared with the performance of the Meiko Elan Widget library and the IBM SP2.