Objective: The authors investigated the intraoperative treatment effects of Prostaglandin E1 (PGE1) for extension of the anhepatic phase and improvement of survival in a rat liver transplant model. Background: Cross- clamping the inferior vena cava and the portal vein during liver transplantation causes severe pathophysiologic changes during surgery. The time of the anhepatic phase is strictly limited and results in a very tenuous period during the liver transplant operation. Methods: Prostaglandin E1 was infused at 0.5 μg/kg/min into five subgroups of rats with 20, 30, 40, 60, and 80 minutes of anhepatic phase during transplantation. Bile secretion, serum aspartate transaminase (AST), lactic dehydrogenase (LDH), and blood gas analysis were studied in the 30-minute subgroup. The results were compared with the sham-operated and control groups. Results: Intraoperative treatment with PGE1 extended the maximal anhepatic phase from 30 minutes in the sham- operated group up to 80 minutes, and increased survival. Significant changes in the PGE1 treated rats in the 30-minute subgroup included an increase of bile flow and bile salt output and decrease of AST and LDH activities after surgery. Blood gas analysis showed a decrease in acidosis and hypercarbia at the end of the anhepatic phase. Conclusions: The PGE1 treatment increased survival with extended anhepatic phase during rat liver transplantation. The beneficial effects can be attributed to its biologic activities.