The effects of ZK-118.182, a stable analogue of PGD2, were evaluated in an endothelin-1-induced cerebral ischemia rabbit model. Ischemia was induced by endothelin-1 injection (0.25 ng bolus) into subcavian artery and ischemic changes were assessed histologically by the number of ischemic neurons in the brain stem. ZK-118.182 (2 μg/kg, bolus into subclavian artery) reduced the number of ischemic neurons when injected 20 min after endothelin-1 injection. Iloprost, a stable analogue of PGI2, was also effective in reducing the number of ischemic neurons in a dose of 0.5 μg/kg (bolus into subclavian artery). The results suggested that ZK-118.182 has a patent antiischemic effect which is comparable to that of iloprost in rabbits.