The current study aimed to assess the antiulcerogenic impact of mesenchymal bone marrow stem cells (BMMSCs) against gastric ulcer induced by the use of piroxicam in rats and to compare this effect with the antiulcer drug "Pantoloc ®" proton pump inhibitors. The study included histological, histochemical, immunohistochemical and ultrastructural examination in stomach of rats in different study groups. In the ulcerated group, the glandular region of the stomach displayed clear mucosal lesions occurring as perforations along the stomach axis. In addition, stomach displayed degeneration of surface mucous cells accompanied by pyknosis, vacuolation among parietal cells in ishmus region, basal region with vacuolated chief cells and karyolitic nucleus of parietal cells. Moreover, Stomach sections of ulcer model rats showed intensive immunoreactivity to cytokeratin 20, Cox 2 and PCNA. Findings of the present study have shown that BMMSCs have an ameliorative effect against piroxicam-induced gastric ulcer in rats. Collectively, the proposed work has shown that BMMSCs have a curative capacity as an antiulcer due to their high antioxidant activity. Further studies are required in molecular levels to understand the mechanism of action during treatment.