Abstract: Cinnamomum zeylanicum (family: Lauraceae) commonly known as cinnamon is cultivated throughout the world, mainly for its bark, a spice used as flavouring agent. The objective of the present study was to study, the effect of C. zeylanicum bark suspension on gastric and duodenal ulcers in rats. The two doses of C. zeylanicum were evaluated for ulcerogenic potential and antiulcer effects. The antiulcer study was carried out in acetic acid induced chronic gastric, pylorus ligation induced gastric, ethanol induced gastric, stress induced gastric, indomethacin induced gastric and cysteamine induced duodenal ulcers. In all these models, the common parameter determined was ulcer index. The higher dose of the cinnamon bark (100 mg kg-1, p.o.) produced a significant protection in the development of the gastric ulcers in all the models whereas the low dose of the bark (10 mg kg-1, p.o.) was not effective in any of the models. The effect produced by high dose of cinnamon (100 mg kg-1, p.o.) was comparable to that produced by standard drugs. The Cinnamon zeylanicum (100 mg kg-1, p.o.) produced an increase in healing of gastric ulcers and prevented the development of duodenal ulcers in rats indicating that it possess both gastric cytoprotective and antisecretory effects.