Neuropsychological performance before and after a rapid (1 week) detoxification treatment, was studied in heroin addicts. Ninety-three opioid dependents (DSM-III) were evaluated with a brief test battery assessing attention, memory and verbal fluency performance prior to their admission to a Detoxification Unit. Significant differences were noted between the addicts' performance and a group of 30 comparable normals, whose intellectual ability was similar. At re-evaluation addicts showed improvement in most measures, including general clinical status. Moreover, no differences between the sample of detoxificated addicts and controls on measures of neuropsychological performance were then detected. No relationship was found between psychopathological symptoms and neuropsychological functioning after the pharmacological detoxification of addicts. The length of addiction or drug consumption were not predictive of neuropsychological impairment in the present sample of heroin addicts.