The in vitro activity of fusidic acid against Staphylococcus aureus is confirmed in clinical studies which demonstrate that this antibiotic in combination with other agents, particularly beta-lactams, is efficacious in non-MRSA septicaemia. Some reports suggest that fusidic acid when used in combination, may significantly diminish the risk of relapse after cessation of therapy. However, in spite of over 30 years of use and its recommendation in a number of guidelines, published evidence is insufficient to allow reliable comment on the efficacy of the antibiotic in the treatment of endocarditis.