Five children receiving long-term total parenteral nutrition (TPN) containing casein hydrolysate as the protein source underwent percutaneous liver biopsies because of the development of cholestasis and abnormal liver function tests. All five demonstrated moderate to severe histopathologic changes. In addition, hepatic aluminum content was determined to be markedly elevated in all cases. Although the hepatotoxicity of aluminum is as yet undetermined, deposition of other metals has been associated with liver damage, and aluminum has been associated with pathology in other tissues. Thus, the possibility that aluminum deposition may play a role in the pathogenesis or exacerbate the course of liver dysfunction associated with TPN should be considered.