Between January 1987 and December 1990, 179 patients (131 men, 48 women) infected with human immunodeficiency virus type 1 (HIV-1) were admitted 408 times to St James's Hospital, Dublin. One hundred and thirty-two (73.7%) patients were intravenous drug users. The commonest cause of admission was bacterial lower respiratory tract infection (84 patients, 21%). At the time of study 95 (53%) patients fulfilled Centers for Disease Control (CDC) criteria for stage IV disease. HIV antibody status in 26 of these patients with stage IV disease was unknown prior to their admission to hospital with symptomatic disease. Pneumocystis carinii pneumonia was the most frequent stage IV defining diagnosis. The mean length of hospital stay for patients with CDC stage II/III and stage IV disease was 8.5 (median 7) and 13.5 (median 8) days respectively.