Message Passing Interface (MPI), a communication library for both parallel computers and workstation networks, has been developed as a proposed standard for message passing and other related operations. It is aimed to provide the parallel programming community with the portability, scalability and efficiency needed to develop applications and parallel libraries for efficient use of current and future high performance systems. New standards, such as MPI, require new tools which will help to use them. In this paper we present Java based case tool for writing MPI programs. In general a case tool is a computer-based product aimed at supporting one or more software engineering activities within software development. As we show in the paper our system offers automatic MPI code generation features for both C and Fortran assuring high efficiency of the application. Support of expert system is a significant feature of the system.