All potentially significant coagulase negative staphylococci (which had previously been called Staphylococcus epidermidis) were subjected to further biochemical testing to establish their true species according to newly proposed identification criteria. Antibiotic susceptibility determinations were also done on these isolates. The majority of these isolates were from bloods, intravenous catheter tips, urines, and wounds and abscesses. Analysis of over 300 isolates showed that 75% were S. epidermidis and 25% were other coagulase negative species, with Staphylococcus haemolyticus and Staphylococcus hominis being the 2nd and 3rd most common species. S. haemolyticus and S. epidermidis were the 2 species most often resistant to multiple antibiotics. Species identification can be useful in some instances in helping to determine the clinical significance of an isolate and also in determining the currently unknown pathogenic potential of species other than S. epidermidis. Species identification of potentially significant clinical isolates was transferred to the diagnostic laboratory service and is now done routinely using the methods and criteria developed during this study.