A 38-yr-old homosexual man developed fever, diarrhea, and weight loss. An upper gastrointestinal examination revealed terminal ileitis, and stains of stool revealed acid-fast bacilli that were subsequently identified as Mycobacterium avium-intracellulare. Antimycobacterial therapy was associated with weight gain and loss of fever and diarrhea. Several months later, cutaneous Kaposi's sarcoma was observed. When the patient developed strictures in the terminal ileum, a surgical resection was performed. Numerous granulomas and acid-fast bacilli, later identified as M. avium-intracellulare, were present in the resected terminal ileum. This report demonstrates that infection of the terminal ileum with M. avium-intracellulare in a patient with acquired immune deficiency syndrome can present with a clinical and radiologic picture resembling Crohn's disease. It also demonstrates symptomatic improvement of this infection temporally related to the administration of antimycobacterial therapy and the ability of an acquired immune deficiency syndrome patient to tolerate major abdominal surgery.