Fortran D is a version of FOrtran enhanced with data decomposition specifications. Case studies illustrates strengts and weaksnesses for the prototype Fortran D compiler when compiling linear algebra codes and whole programs. Statement groups, executin contiisons, inter-loop communication optimizations, multi-reduction, and array kills for replicated arrays are identified as new compilation issues. On the intel iPSC/860 , the output of the prototype Fortran D. compiler apprroaches approaches the performance of improvement for linear computations, but needs improvement for linear algebra and pilelined codes. The Fortrran D. compiler outperformance the CM fortran compiler (2.1 beta) by a factor of four of more on the TMC-5 when not using vector units. Better analysis , run-time support, and flexibility are required for th prototype compiler to be useful for a wider range of programs