Effect of China-made isocrystal pirenzepine ( IPRZ ) on experimental ulcer produced by reserpine in rats was studied & the antiulcer effect of China-made IPRZ was compared with that of China-made PRZ. Our results showed that China-made IPRZ given by either sc ( 25-100 mg/kg ) or ig ( 25-100 mg/kg ) exerted a marked antiulcer effect on reserpine-induced gastric ulcer in rats.The antiulcer effect was increased with the increase of dose of China-made IPRZ. When China-made IPRZ was given by sc, its antiulcer effect was as potent as China-made PRZ, but when it was given by ig, its antiulcer effect was lower than China-made PRZ .This result suggest that the bioavailabili-ty of China-made IPRZ given by ig was lower than China-made PRZ.