Pericarditis with tamponade due to cytomegalovirus in the acquired immunodeficiency syndrome. A 35-year-old male homosexual with AIDS presented with headache and fever and was found to have cryptococcal meningitis. During the patient's hospital course, his hemodynamic status deteriorated as a result of pericardial tamponade. Antemortem analysis of the fluid was unrevealing; however, postmortem examination of the pericardium revealed typical intranuclear inclusions of cytomegalovirus infection. Cytomegalovirus should be included in the differential diagnosis of pericardial effusion in patients with AIDS. 