Thirty-one patients with Wilson's disease were evaluated with detailed neurologic and medical examinations. Mean age (+/- SD) at onset was 21 +/- 5 years and at examination was 28 +/- 6 years. Of the 90% of patients who were first treated with penicillamine, 31% deteriorated initially despite therapy, and half never recovered to pretherapy baseline. At the time of our evaluations, the most common neurologic findings were dysarthria (97%), dystonia (65%), dysdiadochokinesia (58%), rigidity (52%), gait and postural abnormalities (42%), and tremor (32%). Chorea and dementia were rare. Twenty-two patients underwent magnetic resonance imaging. All but one of the 19 symptomatic patients had abnormal scans. The three asymptomatic patients had normal scans. Most lesions were seen in the caudate, putamen, subcortical white matter, midbrain, and pons. Generalized brain atrophy was also common. Lesions were less common in the thalamus, cerebellar vermis, midbrain tegmentum, globus pallidus, red nucleus, and dentate nucleus. Dystonia and bradykinesia correlated with putamen lesions, and dysarthria correlated with both putamen and caudate lesions.