The effects of the anticoagulants, heparin and low molecular weight heparin (LMWH), and the antiplatelet agents, prostaglandin E1 (PGE1) and aspirin, on endotoxin-induced renal insufficiency not induced by prerenal factors, were investigated using rabbits to evaluate the clinical usefulness of these drugs and their possible involvement in the activation of hemostasis in renal insufficiency. The intravenous administration of PEG1, at 0.4 microgram/kg/min, or aspirin, at 5 mg/kg, significantly restored all the parameters of renal function measured in the present study, namely, effective renal plasma flow, glomerular filtration rate and urine N-acetyl-beta-D-glucosaminidase, as well as histological renal ischemic changes. On the other hand, neither heparin nor LMWH, even at a high dose, improved any parameter. As the antiplatelet effect is the common property of PGE1 and aspirin, it is suggested that the activation of platelets may be prerequisite to the occurrence of renal insufficiency induced by endotoxin. The results of this study thus show that PGE1 or aspirin may be applied in clinical use for renal insufficiency complicated by sepsis or endotoxemia.