The present study aimed to describe the cognitive status of a group of HIV-positive asymptomatic intravenous drug users (IVDU) and changes which occurred over a 12-month follow-up period. Forty-two HIV positive IVDU were selected and matched for age, sex, educational level and pattern of drug abuse with 39 seronegative IVDU controls. Baseline and follow-up evaluation included neuropsychological tests exploring attention, language, memory, logic and visuomotor abilities, biological markers and clinical parameters. About one-third of both seropositive and seronegative subjects showed at baseline slight cognitive deficits, which did not change during the follow-up period.