Peptic ulcer is a major health hazard and is a leading cause of morbidity and mortality. This study aimed to test the therapeutic potential of Mesenchymal stem cells (MSCs) in accelerating healing of aspirin – induced gastric ulcer. Gastric ulcer was induced by oral ingestion of aspirin at a dose of 100 mg/kg/day for 3 consecutive days. Intravenous injection of PKH26 labelled-MSCs was done immediately after oral aspirin consumption for the treated group only. Animals were sacrified 3 and 7 days after injection. Fundic specimens were processed for hematoxylin and eosin, Masson's trichrome, Periodic Acid Schiff Reaction and immunohistochemichal stain for CD44. Mean area % of collagen fibers, optical density of PAS reaction and mean number of CD44 immunostained cells were done. The ulcer-induced group showed sloughing of the surface epithelium, congestion of blood vessels in the mucosa, marked leucocytic infiltration and widening of the submucosa. Increased collagen fibers content and loss of PAS reaction from the denuded areas were also noted. MSCs-treated group showed regenerated surface epithelium with restoration of the normal glandular architecture and narrowing of the submucosa. Decreased collagen fibers content and strong positive PAS reaction at the surface epithelium, as compared with the ulcer-induced group were demonestrated. Spindle-shaped cells exhibiting brown cytoplasmic immunoreactivity to CD44 were localized in the deep part of the mucosa and submucosa. These findings suggest that the injected MSCs successfully accelerated gastric ulcer healing.