Objective: To evaluate the antiulcer activity of the leaf extract of Osyris Quadripartita ( OQ) in albino wistar rats. Methods: The 80% methanolic extract of OQ leaves was subjected to acute toxicity test and phythochemical analysis. The extract's anti-ulcer activity were studied using the pylorus ligation and ethanol induced ulcer model both for dose dependent (100, 200, 400mg/kg) and time dependent (200mg/kg for 10 & 20 days) studies. Volume, pH, total acidity, ulcer score and ulcer index were determined for pylorus ligation induced ulcer model and ranitidine 50mg/kg (R50) was used as a standard dug. In ethanol induced ulcer model ulcer score and ulcer index were determined and sucralfate 100mg/kg (S100) was used as a standard drug. Conclusion: The 80% methanolic extract of OQ exhibited anti-ulcer activity which is comparable to the standard drugs and this could be attributed to the possible presence of one or more secondary metabolites. This supports the ethnomedicinal use of leaves of Osyris quadripartita.