Neuropsychological functioning in opiate addicts has been infrequently studied and results have been contradictory. In the current study, 72 opiate addicts, 60 epileptics, and 29 demographically comparable normals were tested using a brief neuropsychological test battery. Few significant differences were noted between the performance of addicts and the subjects in comparison groups, and these were in a direction suggesting better functioning in the addict sample. Follow-up re-evaluation of addicts showed stability in most measures but significant improvement in measures of intelligence quotient, verbal fluency, and new associative learning. Performance on neuropsychological tests was shown to be independent of current or past levels of opiate use and to be of little prognostic significance in relation to treatment outcome. In contrast, a comparatively strong association was noted between measures of neuropsychological functioning and educational achievement.