Exclusive monotherapy with zinc in symptomatic Wilson disease is controversial. Seventeen symptomatic patients with Wilson disease were treated with zinc only. The mean age at diagnosis and start of treatment was 18 years (range 13–26) with approximately half presenting as adolescents. Presentation was exclusively hepatic, exclusively neurologic, and combined in seven, five, and five patients, respectively. The median follow-up was 14 years (range 2–30). At baseline, two of the 12 patients with hepatic disease exhibited decompensated cirrhosis, five exhibited compensated cirrhosis, and five had less severe disease. Both patients with decompensated cirrhosis improved to a compensated state after initiation of therapy. Two of the five patients with initial compensated cirrhosis progressed to decompensated state, and three remain stable. Three of the five patients with moderate or mild liver disease remain stable and two improved. Apart from decreasing bilirubin levels, no significant changes occurred in the liver biochemistry or function during long-term follow-up. Nine of 10 neurologic patients improved markedly and one deteriorated. Two patients with exclusively neurologic presentation developed liver disease during zinc treatment. Two patients with exclusively hepatic presentation developed mild neurologic symptoms. According to 24-hour urinary copper excretions (213 ± 38 versus 91 ± 23 μg: P = 0.01) and serum non–ceruloplasmin-bound copper concentrations (11 ± 2 versus 7 ± 1 μg/dL: P = 0.1) at the end of follow-up, the efficacy of decoppering was less in the exclusively hepatic than in the neurologic group. The prescribed zinc dose and 24-hour urinary zinc excretions tended to be less in the exclusively hepatic group. Conclusion: The outcome of exclusive zinc therapy is generally good in cases of neurologic disease. A less satisfactory outcome in hepatic disease may relate to less efficient decoppering. (HEPATOLOGY 2009.)