We tested the ability of teicoplanin alone and in combination with rifampicin or gentamicin to cure experimental endocarditis and granuloma pouch infections in rats caused by Streptococcus faecalis, Str. sanguis, methicillin-sensitive and -resistant Staphylococcus aureus. Vancomycin and ampicillin were also tested. Teicoplanin was more active than vancomycin and ampicillin. Combinations of teicoplanin with rifampicin or gentamicin were significantly more effective than single drug therapy. These results suggest that teicoplanin could be an interesting alternative to vancomycin in the treatment of serious streptococcal and staphylococcal infections in man.