We have measured zinc levels in serum and urine of healthy controls, patients with liver cirrhosis and patients with cirrhosis and hepatic cancer. In patients with ascitic fluid, we also measured zinc, total protein, albumin and alpha 2-globulin. Basal measurements were performed in blood drawn at 8.00, before the intravenous administration of 8 mg zinc in the form of zinc sulphate. Serum levels were measured at various intervals to a total time of 24 h after overload, and total urine was collected for zinc determinations 24 h before and 24 h after overload. Under basal conditions, cirrhotic patients had lower serum levels and higher rates of urinary excretion of zinc than controls. After overload, blood levels of zinc fell more rapidly in cirrhotic patients than in controls, the former group showing no concomitant rise in urinary zinc excretion, thus suggesting an organic deficit in this trace element. In ascitic fluid, the concentration of zinc was positively correlated with protein content.