Infection with the human immunodeficiency virus (HIV), its complications, and its treatment present a new set of challenging problems to surgeons. Thrombocytopenia related to the acquired immunodeficiency syndrome (AIDS), biliary obstruction caused by cryptosporidiosis, and Kaposi's sarcoma of the intestinal tract are examples of problems unique to AIDS. In addition, patients with ordinary diseases calling for surgery, such as cholecystitis, hernia, and valvular endocarditis, may coincidentally be infected with HIV. Finally, patients in the terminal stages of AIDS may have life-threatening surgical complications, such as bleeding or perforation, that may be surgically reversible but only with questionable benefit to the patient. Surgeons therefore wish to remain up to date on the pathogenesis of AIDS, its secondary infections, and the treatment options for it.