The therapeutic effects of TCV-309, a never platelet activating factor antagonist, on hemodynamics in endotoxin-induced shock were evaluated. Ten Beagle dogs were used under general anesthesia and artificial ventilation. After intravenous injection of endotoxin (3 mg/kg), TCV-309 (1 mg/kg) was administered intravenously to the dogs. The results showed that the depression of mean aortic pressure, cardiac output, left ventricular stroke work index and urine volume which occurred in endotoxin shock was significantly improved by administration of TCV-309. These results suggested that TCV-309 was a useful therapeutic for the circulatory disturbance in endotoxin shock.