The effects of the combination of clindamycin and rifampicin against 21 strains of clindamycin-susceptible and 19 strains of clindamycin-resistant Staphylococcus aureus were studied by the time-kill method. For the clindamycin-susceptible strains, clindamycin prevented the re-growth of Staph. aureus in the presence of rifampicin. For the clindamycin-resistant Staph. aureus strains, indifference was demonstrated against the majority of strains, with only a few strains showing synergism or antagonism.