A case is reported of autoimmune thrombocytopenic purpura in a narcotics addict with antibodies against human immune deficiency virus (HIV). Three points need stressing: 1) HIV is a new viral cause of autoimmune thrombocytopenic purpura, the first report of which dates from 1985; 2) this bleeding diathesis may be seen more often in normal anaesthetic practice because of the frequent association of intravenous toxicomania with anti-HIV antibodies and thrombocytopaenia. Thus, of the thirty cases detected in two years and followed by our Department of haematology, two were operated on in the orthopaedic unit; 3) the use of intravenous human gammaglobulins is of great interest each time the clinical situation requires a rapid increase in the platelet count, such as before surgery. The usual dose is 400 mg . kg-1 . j-1 for five consecutive days. The response to immunoglobulins is seen in two or three days; their efficacy, in the case described, lasted for five to seven days, this including the postoperative time. Booster doses were followed by a quick increase in platelet count.