Abstract Strains of Staphylococcus aureus were isolated from 360 patients with angular cheilitis. Of these 24 per cent were sensitive to penicillin G, 74 per cent to tetracycline, 93 per cent to fusidic acid and 96 per cent to erythromycin. Twenty per cent belonged to bacteriophage Group I, 9 per cent to Group II, 13 per cent to Group III, 39 per cent miscellaneous and 19 per cent were untypable. A number of phage typing patterns which have been reported for strains associated with specific forms of staphylococcal disease were present in the 360 isolates. In investigations involving cross infection of Staph. aureus, both patients and staff should be examined for evidence of infection at the angles of the mouth.