A group general practice in Dublin's inner city has had extensive experience of intravenous drug users since the late 1970s. Since 1985 a total of 54 human immunodeficiency virus (HIV) seropositive patients have attended the practice of whom 48 are intravenous drug users, four are the children of drug users and two have been infected through sexual contacts. Three patients have developed the acquired immune deficiency syndrome and at least eight have symptomatic HIV disease. Sixty per cent of Ireland's seropositive population have been infected through intravenous drug abuse but nationally only 16% of all intravenous drug users tested are seropositive; in the study practice, however, at least 35% (48/137) of known intravenous drug users are seropositive.