We studied the clinical records of 280 patients admitted to our Hospital between 1985 and 1988, with a positive Elisa test for HIV-related antibodies: 15.71% (44) of these patients exhibited clinical abnormalities related to disease of the CNS. In 6 (13.6%) patients the neurological complication was the first manifestation of HIV-infection. Patients were mainly male homosexuals, in the 30-39 age range. Frequent chief complaints included hemiparesis, headache and behavior disturbances. Cerebral toxoplasmosis was diagnosed in 18 instances. It should be considered the first diagnostic possibility in patients presenting with mass lesions. Meningeal infections were present in 19 cases (cryptococcal in 13, tuberculous in 4, HIV-related in 2). CSF findings in these patients were non specific, except for demonstration of Cryptococcus neofarms on direct examination of CSF or culture studies. CT scans frequently displayed unique or multiple hypodense lesions. The lesions exhibited ring-enhancement in 7 instances, and were non-enhancing in 8 others. Cortical and subcortical atrophy with hydrocephalus ex-vacuum were occasionaly found, and the CT scans were normal in 8 instances. Time from appearance of the various neurological complications to death or clinical resolution was almost always shorter than 6 months. Death was the most frequent outcome, usually occurring within 6 months. Survival in the most of these patients never reached the end of the first year.