Neurotropism of H.I.V. has recently been recognized. More than one third of Aids patients have neurological complications (infections, tumors, multifocal progressive leuko-encephalopathy...) attributed to immunological failure. Necropsy reveals more frequent neuropathology (75%). "AIDS Dementia Complex" (A.D.C.) has been described. Neuropsychological impairment (and personality alteration) is frequent (20-40%) even in asymptomatic patients. H.I.V. infects the C.N.S. early in the course of viral infection and prior to the development of classical associated neurological abnormalities. Mental disorders are frequent: anxiety, depression, suicidal behavior, etc. They can be psychological reactions, although they are often already present before H.I.V. infection in "high risk groups". The signification of psychosis is discussed. Overview of literature.