The early organic mental disorder, caused by the human immunodeficiency virus type 1 (HIV) in the drug dependents (DD), if it is not taken into account, can disturb the diagnosis of the neuropsychiatric and the toxic disorders. The authors attempt to outline, with several neuropsychological tests (visuo-perceptual, memory, attention) and with the physical and neurologic exploration, if cognitive abnormalities are present in two groups of DD after detoxification period. The first group is infected by the HIV (n: 48), and the second one is not (n: 33). Differences can be found only in the Bender visuo-perceptual test, which are not justified by the divergences found between the groups about the drug dependence history and the present drug of abuse intake. The importance of the early diagnosis of these abnormalities is argued in order to get a suitable treatment of the possible neuropsychiatric complications in the DD development, and restrain the extent of the cognitive damage by HIV infection.