The results of a study about psychiatric morbility in patients suffering from HIV infection treated in a psychiatric consulting department of a general hospital are presented. Out of one hundred of individuals studied, 93 showed a diagnosis in Axle I according to DSM-IIIR criteria for mental disorders classification. The diagnosis most frequently found was the one of disorders due to drugs dependence, in 41%; organic mental disorder in 29%; adaptation disorders in 15% and affective one in 5% of cases. In sixteen patients of the sample a follow-up was carried out finding ad evolution towards dementia. Diagnostic difficulties of this population and usefulness of carrying out a revision of diagnostic classifications usually employed are debated.