OBJECTIVE: To date, there have been no formal investigations of neuropsychological performance in patients with Tourette's disorder who are taking psychotropic medications. The authors conducted this study to provide such information. METHOD: They examined the neuropsychological performance of 96 patients 6-18 years old who met DSM-III-R criteria for Tourette's disorder; 51 of these patients were taking neuroleptic medications and 45 were not. The groups were well matched with regard to age, sex, education, and duration of symptoms. Each group was given a complete neuropsychological test battery as well as instruments rating symptoms of Tourette's disorder, obsessive- compulsive characteristics, and other behavioral disturbances. RESULTS: The patients taking medications did not differ from those not taking medications on any of the neuropsychological, intellectual, or educational measures. In addition, the groups did not differ with regard to level of Tourette's disorder symptoms. CONCLUSIONS: The results of this investigation suggest that patients with Tourette's disorder who do not experience intolerable side effects from neuroleptic medications are able to perform on educational, intellectual, and neuropsychological tests at a level comparable to that of unmedicated patients. These results have positive implications for patients with Tourette's disorder who respond to neuroleptic medications.