Tuberculosis has not been well documented as a complication of the acquired immunodeficiency syndrome (AIDS). We studied 48 cases of mycobacterial diseases among a group of 136 adult patients with AIDS over a 43-month period. Twenty-nine of them had severe and unusual manifestations of disease due to Mycobacterium tuberculosis, predominantly extrapulmonary and disseminated. Tuberculosis was more common among Haitians (4/8) and intravenous drug abusers (24/102) than among homosexuals who did not abuse drugs (0/22). Twelve of 21 patients with tuberculosis who were treated responded well, whereas three developed progressive disease indicative of treatment failure. Severe and unusual presentation of overwhelming tuberculosis in appropriate clinical circumstances may be considered an infection predictive of the presence of AIDS.