We reviewed the records of 42 patients with Wilson's disease participating in a zinc acetate treatment protocol and interviewed 17 of them. Five of the patients studied were asymptomatic. A significant number of symptomatic patients (64.8%) reported psychiatric symptoms at the time of initial presentation. These symptoms were severe enough to warrant psychiatric intervention in almost half of all symptomatic patients before the diagnosis of Wilson's disease was made. Personality changes, particularly irritability and aggression, were most commonly described (45.9%), followed by depression (27%). Cognitive changes, anxiety, psychosis, and catatonia, while less frequent, also occurred. These data underscore the need to include Wilson's disease in the differential diagnosis of psychiatric disorders.