Cognitive deficits in patients with structural lesions of the basal ganglia (e.g., Huntington's disease) commonly include slowed processing, reduced verbal fluency, difficulty switching set, impaired egocentric spatial ability, poor recall, and impaired acquisition of motor skills. The goal of this study was to determine if patients with obsessive-compulsive disorder (OCD) would have a similar pattern of cognitive dysfunction. A battery of neuropsychological tests, including reaction time-based measures of cognitive processing speed and a test of procedural, motor-skill learning, was administered to 17 unmedicated OCD patients and 16 age-and education-matched normal controls. Eleven individuals with trichotillomania, matched with the OCD patients on age, education, age at symptom onset, depression, and anxiety were also tested. Contrary to expectation, neither the OCD nor trichotillomania patients were impaired on any of the measures in the battery. The essentially normal performance by these patients suggests that the brain regions responsible for cognitive dysfunction in patients with Huntington's disease may differ from those associated with OCD.