A young female patient with a long history of intravenous drug abuse died after a fulminant course of aplastic anemia. At postmortem examination, she was found to have multinucleate giant cells and immunocytochemical evidence of human immunodeficiency virus (HIV) infection of the central nervous system. This case raises the possibility that HIV infection contributed to the patient's aplastic anemia, and suggests that HIV-associated giant cells might be found retrospectively or prospectively within the brains of patients who die of conditions other than those narrowly defined as acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC). It furthermore emphasizes that HIV infection of the nervous system is not necessarily accompanied by clinically apparent neurological disease.