Mental disturbances associated with acquired immunodeficiency syndrome (AIDS) are related not only to profound psychosocial stress, systemic diseases, and neoplasms or opportunistic infections within the central nervous system (CNS); they are also related to the direct neurotoxicity of the etiologic human immunodeficiency virus (HIV), producing an array of both insidious and acute affective, cognitive, and behavioral dysfunction that can mimic many neuropsychiatric disorders. The precise mechanism of this direct neurotoxicity is not known, nor have the frequency, clinical course, or methods of early diagnosis been clearly established; however, a critique of 56 clinical reviews or case reports regarding approximately 800 subjects suggest that at some point following infection an HIV-induced dementia is extremely common, as are marked histopathological changes throughout the CNS. Treatment strategies are discussed.