Five patients with acquired immune deficiency syndrome (AIDS) developed clinical evidence of mild to severe cardiac dysfunction confirmed by nuclear angiography and echocardiography. In 4 patients who were studied postmortem there was no evidence of myocarditis, valvular, or ischemic heart disease. Cardiac involvement in patients with AIDS may include pericardial and myocardial involvement by opportunistic pathogens or Kaposi's sarcoma, subclinical myocardial dysfunction, or an as-yet unexplained cardiomyopathy.