Metabolic disturbances in the canine liver during warm ischemia by Pringle's method for 60 minutes and the role of Coenzyme Q10 (CoQ10), Prostaglandin E1 (PGE1) and ONO-3708, TXA2 receptor antagonist, were studied. Mongrel dogs were divided into five groups; control group, group of liver ischemia without drugs, groups of liver ischemia with CoQ10, PGE1 and ONO-3708 pretreatment. Metabolic rates of PGI2, TXA2, insulin, glucagon and glucose and production of lipid peroxides in the five groups were measured at the points before Pringle's procedure, 5 minutes, 60 minutes and 120 minutes after declamping. In the group of ischemia without drug administration, the hepatic metabolism of PGI2, TXA2, insulin and glucose were decreased after declamping. The metabolism of glucagon, however, was not disturbed by warm ischemia. The production of lipid peroxides increased at 5 minutes after declamping. In the groups of CoQ10, PGE1 and ONO-3708 pretreatment, changes of PGI2, TXA2 and insulin metabolism in the liver were improved, and an increased production of lipid peroxides by warm ischemia was normalized. This study suggests that CoQ10, PGE1 and ONO-3708 protect liver damage by warm ischemia as results of improvement of metabolic disturbances of PGI2, TXA2, insulin and suppression of lipid peroxides production.