ABSTRACT— The protective effects of PGE1 on ischemia-related liver damage were evaluated in dogs. Ninety minutes warm hepatic ischemia was induced by the total clamping of hepatic inflow vasculatures with portal bypassing. The survival rate improved up to 62.5% when PGE1 was administered intravenously prior to ischemia, while no dog survived for longer than 1 week in the nontreated group. Hepatic ATP content was restored up to 80% of preischemic level 2 h after reflow in the PGE1 pretreated group, compared to 55% recovery in the nontreated group. Complete normalization of hepatic energy charge and rapid decrease of lactate were also seen in the PGE1 group. The clearance rate of intravascular lipid emulsion remained fairly normal in the PGE1 group, thereby suggesting well-preserved hepatic reticuloendothelial functions. The serum activities of β-glucuronidase, GOT and GPT were suppressed in the PGE1-pretreated group, thereby implying a well-protected hepatic integrity. The histology revealed well-preserved hepatic architecture. The remarkable cytoprotective effect of PGE1 on hepatic ischemia shown in this study indicates that PGE1 warrants further study for protection of ischemically compromised hepatic allografts.