Objective: To investigate the effect of bone marrow mesenchymal stem cells (MSC) on the variation of intestinal permeability damaged by superior mesenteric artery ischemia and reperfusion. Methods: Bone marrow mesenchymal stem cells were isolated from cavity of tibias and femurs of male Sprague Dawley rat in a sterile condition, and were cultured and proliferated in plastic dishes. 10 week old female Sprague Dawley rats were randomly divided into three groups:group A (sham group), group B (MSC group) and group C (saline group). In group B and group C, the superior mesenteric artery (SMA) of the animals were seperated and occluded by non-invasive vascular clamp for 45 minutes. Immediately after removing the vascular clamp,1×10~7 MSC suspended in 0.5 ml sterile L-DMEM and the same volume of normal saline was submucosally injected into the small intestine at ten different points in group B and group C, respectively. In group A, the animals were only underwent laparotomy without clamping the SMA. 3 days and 6 days after the operation, 100 mg lactulose and 50mg mannitol dissolved in 2 ml distilled water were administrated by oral gavage and urine during 6 h experiment was collected for assaying the L/M ratio before sacrificing the animals. The donor derived MSC was identified by Y chromosome in situ hybridization in ileum tissue, and the serum D-lactate level was determined. Results: The donor derived MSC could home to the ischemia/reperfusion injured intestinal mucosa, and the intestinal permeability was much lower in group B (MSC group) than that in group C (saline group)(P<0.05). Conclusion: Mesenchymal stem cells can reduce the small intestinal mucosal permeability impaired by ischemia/reperfusion, and can participate in the preservation of integrity of the damaged gut mucosal mechanical barrier.