To compare the adherence properties of Staphylococcus saprophyticus and Staphylococcus epidermidis in vitro studies were conducted with clinical isolates and cell culture monolayers (Hela, Vero, MDCK). Staphylococcus saprophyticus exhibited greater cell adherence, but no significant difference in mean urine growth rate. Its cell-adherence properties seem to explain in part its virulence.