Between 1950 and 1991 the authors have treated 45 adults with primary septic arthritis of the hip, not including tuberculosis. The mortality rate was 13%. There is an accompanying septicaemia, or, more commonly, a bacteraemia, and other general and local factors are often present. The diagnosis may be obvious, but in 50% of cases the presentation may be atypical and the clinical diagnosis uncertain. Confirmation of the diagnosis is by a positive culture from the aspirate, and a Staphylococcus is the usual organism found. The various methods of management used are discussed and the literature analyzed. Wide drainage of the hip is recommended. Arthrodesis is now rarely necessary, and a total replacement arthroplasty may be undertaken when the infection has been controlled. Six out of seven such procedures carried out in their unit in the last 10 years have been successful.