A morphologic sequence of progressive hepatic injury is demonstrated in an immature infant who received TPN for 148 days. Because immature infants are susceptible to multiple pathophysiologic insults, it is presently impossible to isolate a single etiologic agent responsible for hepatic dysfunction. It is important for physicians caring for immature infants to establish through biochemical and morphologic monitoring that appropriate duration for TPN which is not likely to lead to irreversible hepatic injury.