Whole-cell-polypeptide profiles obtained by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) were used in conjunction with the API-Staph technique to identify different strains of Staphylococcus aureus, S. epidermidis, S. saprophyticus and S. capitis. Complete concordance of results from both techniques was achieved with all strains examined. Visual analysis of the polypeptide patterns and comparison by use of the coefficient of Dice showed minor differences in band pattern between strains of the same species but each species produced a pattern distinguishable from that of any other. The results suggest that although SDS-PAGE can be used to identify staphylococcal species, this type of analysis will not readily provide the basis for a typing method.