A prospective survey of 38 HIV1-infected infants has been performed. Thirty-four percent of the patients expressed neurological abnormalities. Three main clinical entities of various intensity have been defined: 8 patients had severe intellectual and motor dysfunctions associated with a bucco-lingual dyspraxia; in 4 patients, the intellectual and motor alterations were less intense but were associated with a severe bucco-lingual dyspraxia; finally one patient had no clinical symptomatology but a chronic lymphocytic meningitis. No opportunistic infection of the CNS was observed. The neurological alterations were correlated in intensity with the immunological dysfunction. CT scans were normal or showed cerebral atrophy in most cases. CSF were normal in 12 cases and a pleiocytosis was observed in one case. However, in 4 of the 6 tested cases, anti-HIV antibodies were detected in CSF.