This study tries to demonstrate the importance of using follow-up trials and taking anxio-depressive status into account while interpretating cognitive impairment in HIV-infected subjects. Subjects included were : 18 HIV carriers, mostly homosexual, belonging to CDC groups II (4), III or IVC2 (7) and IV (7), selected within a cohort of 63, as having been assessed 3 times, with no focal or identified brain disease at entry. Our methods were : 1) psychiatric interview based on DSM III-R criteria, clinical scales (Spielberger's STAXI and the MADRS) and cognitive questionaries; 2) neuropsychological evaluation including 16 subtests screening attention, memory, visuo-spatial function, motor dexterity, psychomotor speed, and language; 3) repeated assessment within a period ranging from 6 to 21 months. Results : At entry, cognitive status was impaired for 14 subjects (2 II, 5 III or IVC2, 7 IV). Disorders had disappeared for 7 subjects (2 II, 2 IVC2 and 3 IV) at following assessments allowing us to conclude on a psychogenic origin. For 7 subjects, cognitive status had either remained constant (3 III and 2 II) or had worsened within 7 to 17 months (2 IV), whereas psychiatric symptoms had decreased, implying HIV encephalopathy. Follow-up trials including 3 neuropsychological and psychiatric assessments and neuroimagery, if necessary, were required to ascertain the causes of cognitive impairment consequently attributed to anxio-depressive symptoms or HIV encephalopathy in 14 subjects.