The in vitro activity of the oxazolidinone linezolid was compared with the activities of vancomycin and teicoplanin against 450 Gram-positive clinical isolates, including a variety of multiply resistant strains. Linezolid inhibited all microorganisms tested at < or = 4 mg/L, including methicillin- and teicoplanin-resistant staphylococci, glycopeptide-resistant enterococci, penicillin- and multiply resistant pneumococci and viridans streptococci, and erythromycin-resistant beta-haemolytic streptococci. The MIC(90) of linezolid for all isolates was 2 mg/L.