The levels of cupriuresis before and after DL-Penicillamine have been investigated in 168 cases. The mean copper excretion before Penicillamine in chronic activ liver disease, chronic persistant hepatitis, cirrhosis and in transitional cases of aggressiv chronic hepatitis and primary biliary cirrhosis ranged from 29 gamma to 48 gamma/24 hr.; however, in some cases the daily copper excretion exceeds 100 gamma, as well in subjects with liver disease as in normals too. After ingesting 900 mg DL-Penicillamine the mean values of cupriuresis ranged from 500 gamma to 600 gamma/24 hr. Abnormal results were found in about 15% of those subjects with liver diseases; in only two of 20 cases with hypercupruria after Penicillamine Wilson's Disease was established.