It is well documented that human immunodeficiency virus (HIV) can infect the central nervous system. Neurological dysfunction occurs frequently in acquired immunodeficiency syndrome (AIDS) and most commonly in the form of a subacute HIV-encephalitis. The pathological abnormalities in patients with subacute HIV-encephalitis are most prominent in subcortical structures, notably in the cerebral white and deep gray matter. The patients frequently develop abnormalities in cognitive, motor and behavioral functions. The infected cells are predominant lymphocytes and macrophages. The production of cytokines by these cells appears to be a central factor in the pathogenesis of subacute HIV-encephalitis. The central nervous system can function as a reservoir of HIV infection. Neuropsychological assessment is a sensitive method for documentation of early brain involvement by HIV infection. The HIV-associated neurological abnormalities may be partially ameliorated by administration of zidovudine (AZT).