Background: There is accumulating evidence that a polyphenol present in olive oil, OLEUROPEIN, has antioxidant, anti-inflammatory and anti-apoptotic effects. This study aimed at determining the anti-apoptotic effect of OLEUROPEIN (Ole) on dexamethasone-induced apoptosis of mouse thymocytes. Method: Mice were randomly divided to four groups as follow: Dexamethasone (Dex)-treated group (20 mg/kg; single dose), Ole-treated group (20 mg/kg per day), Dex plus Ole-treated group, and vehicle group. Sections of thymus were taken 16 hours after dexamethasone injection and studied for histopathological and immunohistochemistry assessment. Result: Further characteristics of degeneration in thymocytes were observed in the Dex group compared with the Dex plus Ole group. Compared with the Dex group (10. 94± 3. 35), positive staining for Bax in thymocytes decreased in Dex plus Ole group (2. 64± 1. 26), but remained higher than the Ole (0. 65± 0. 30) and vehicle (0. 67± 0. 29) groups. Compared with the Dex group (2. 94± 0. 42), positive staining for Bcl-2 in thymocytes increased in Dex plus Ole group (12. 24± 1. 84) yet was lower than the Ole (14. 94± 1. 54) and vehicle (18. 93± 3. 54) groups. Conclusion: Our results suggest that dexamethasone-induced apoptosis is subsided by OLEUROPEIN.