Acquired Immune Deficiency Syndrome (AIDS) is a clinical entity that is part of a spectrum of immune dysfunction found in specific high risk groups, among them intravenous drug users. In drug users AIDS almost always presents as an opportunistic infection, usually Pneumocystis carinii. The leading etiologic hypothesis is of a viral agent acting, it is possible, on a previously immuno-compromised host. Recent reseach at hospitals affiliated with the Albert Einstein College of Medicine, where an unusually large proportion of AIDS patients are drug users, is described. Suggestions are advanced for the management of IV drug users with immune dysfunction.