Two years of continuous therapy promoted a significant overall amelioration in a 10-year-old boy affected by an hepatic form of Wilson's disease in which zinc sulphate was the sole therapy. In particular, liver function returned to normal and hepatic histology also improved. The parameters characterizing copper metabolism were kept under good control, and a decrease in copper concentration was found in both erythrocytes and liver. The copper balance study performed during the 25th month of treatment showed that oral zinc was still efficiently inhibiting the intestinal absorption of copper. No side effects have been reported so far.