A group of n. 86 HIV-pts. (CDC stages from II to IV) were cross-sectionally studied with neuropsychological and neurophysiological methods. The percentage of abnormalities detected even among pre-AIDS stages is very high (from 25 to 50% of the cases). Sensibility and specificity of the above investigations is discussed. Their possible predictive role (evolution to successive stages of asymptomatic pts. and development of CNS pathology) is also evaluated based on a medium-term clinical follow-up (18-24 months).