This paper presents a comparison of three programming models—OpenMP, HPF, and MPI—applied to a diphasic compressible fluid mechanics code. The parallelization analysis is conducted, and the authors also present the experimental results obtained on various platforms: a Compaq Proliant 6000 (4 processors), a Cray T3E-750 (300 processors), an HP Class V (16 processors), a SGI Origin 2000 (32 processors), a cluster of PCs, and a COMPAQ SC 232 (232 processors). These experimental results will be discussed according to the following criteria: efficiency, scalability, maintainability, developing costs, and portability. As a conclusion, the authors present the parallelization strategy recommended for codes comparable to ECOSS.