ScalaBLAST is a high-performance multiprocessor implementation of the NCBI BLAST library. It supports all 5 primary program types (blastn, blastp, tblastn, tblastx, and blastx) and several output formats (pairwise, tabular, and XML). It will run on most multiprocessor systems which have MPI installed, and can run over a wide variety of interconnects, including infiniband, quadrics, and ethernet. It is designed to run a large number of queries against either large or small databases. It parallelizes the BLAST calculations by dynamically scheduling them across processors using a fault-resilient scheme.