DNA Strider is a user-friendly Macintosh program designed for analysis of molecular sequence data. The program shows great versatility in choice of genetic codes, restriction enzymes, algorithms for hydropathy plots, and interconversions between types of sequence data. It is very straightforward and interacts well with other sequence and phylogenetic analysis packages, importing and exporting data easily. The graphic outputs can be used directly for manuscript-quality figures, or exported to more sophisticated text or graphic programs.