Forty-five patients with Wilson's disease (WD) were prospectively studied: 27 had neurological deficits, 12 hepatic signs, and 6 were asymptomatic. Kayser-Fleischer rings occurred in 23 of the neurological patients and in only 4 of the hepatic patients. Neurological features were extremely variable with respect to frequency and severity. Most frequent were dysdiadochokinesis (25 patients), dysarthria (23), bradykinesia (17), and posture tremor (14). Fifteen, mainly long-term treated patients, presented with rather discrete neurological abnormalities which predominantly consisted of dysarthria and various forms of tremor. Eight patients had a parkinsonian type of neurological WD associated with signs of an organic mood syndrome. Three patients were predominantly hyperkinetic, presenting with dystonic and choreatic movements. In 1 patient, ataxia was the predominant neurological feature. There was a clear-cut correlation between the severity of neurological impairment and the restriction in functional capacity. Nine patients were not able to engage in salaried employment or were retired. Psychiatric symptoms and behavioural disorders were common, varying from mild personality and psychological disturbances to severe psychiatric illness resembling psychotic disorders and major depressive syndromes. Significant mental deterioration was not found in the patients. Disturbances of mood were observed in 12 patients, all of whom had neurological abnormalities. There was a history of an attempted suicide in 7 patients, and a history of an organic delusional syndrome in 3.