OBJECTIVE The objective of the following study is to investigate the effect of ovarian sex hormones on gastric ulcer in female rats. METHODS Female rats were treated daily with estrogen (0.05 and 0.1 mg/kg), progesterone (2.0 and 5.0 mg/kg), combined estrogen (0.05 mg/kg) and progesterone (2.0 mg/kg), ranitidine (30 mg/kg) or vehicle for 7 days. Ulcers were induced with aspirin on 7th day. Four hours later, animals were sacrificed and stomach were removed for macroscopic and biochemical examination. RESULTS Estrogen in 0.05 and 0.1 doses showed 32% and 18% of ulcer inhibition, respectively, progesterone 09% and 14% inhibition in 2.0 and 5.0 mg/kg doses, respectively, whereas combined estrogen and progesterone showed 23% and ranitidine showed 60% inhibition. However, the inhibition attained and the stomach malondialdehyde and glutathione levels in sex hormone treated groups were not statistically significant when compared to control group. CONCLUSIONS At the tested doses, these ovarian sex hormones neither worsen nor protect against aspirin-induced gastric lesions in female rats.