A parallelization of a Navier-Stokes solver is presented. The flow solver is based on a multi-block structured grid. The parallelization is performed over the blocks, and the data on the block boundaries is exchanged using the MPI Standard. The parallelized code can also be run in a single processor mode or on a shared memory machine. In order to facilitate the pre- and post-processing a separate program for a domain decomposition has been written. The first tests indicate a good scaleability of the parallelization approach.