The in-vitro activity of levofloxacin was compared with ofloxacin and D-ofloxacin against 130 isolates of Staphylococcus aureaus and 117 isolates of coagulase-negative staphylococci, using the agar dilution method. In general, levofloxacin was equally active or up to fourfold more active than ofloxacin against all staphylococci, including 61 methicillin-resistant S. aureus. In contrast, D-ofloxacin showed little activity against all isolates tested.