Effect of LipoPGE1 on liver injury caused by ischemia-reperfusion were compared with that of PGE1-CD, cyclodextrin clathrated PGE1, in rats. LipoPGE1 (10 micrograms/kg) and PGE1-CD (10 micrograms/kg) were gradually injected into the portal vein 5 min both prior to ischemia and prior to reperfusion. In only the group receiving injections of vehicle alone, rats died within 2 days after the episode of 90-min liver ischemia. The survival rate of all rats treated with LipoPGE1 was higher than that of rats who received vehicle alone, which indicates that LipoPGE1 pretherapy improved the survival of rats after liver ischemia-reperfusion. LipoPGE1 markedly suppressed elevations of GOT, GPT, and LDH, lipid peroxide and aromatic amino acid levels in the plasma caused by ischemia-reperfusion of the liver. When animals were given a single dose of LipoPGE1 prior to reperfusion, LipoPGE1 also suppressed elevations of GOT, GPT, LDH and lipid peroxide levels caused by 30-min of liver ischemia followed by 12-hr reperfusion. These suppressive effects with LipoPGE1 were stronger than those of PGE1-CD. These findings suggest that LipoPGE1 may have therapeutic applications in the treatment of hepatic injury.