A brother and sister who suffered from pruritus since infancy developed hepatic cirrhosis early in life. Although this clinical picture has never been seen in Wilson's disease, Kayser-Fleischer rings in the boy made further studies necessary. Oral radiocopper loading tests administered to both children and to their parents served to exclude Wilson's disease conclusively. Determinations of the concentrations and patterns of bile acids in the serum indicated that the abnormalities observed in these children are not related to errors in bile acid synthesis. Although a defect in bile acid transport is present, it appears to have occurred as a consequence of the liver disease.