Background and Objectives: Colitis is inflammation of the colon which can be transmural or confined to the mucosa. Colitis may be acute or chronic. In case of serious intestinal discontinuity of epithelium, the regeneration capacity of local stem cells is not enough to complete tissue repair. Bone marrow mesenchymal stem cells (BM-MSCs) migrate into the gastrointestinal wall, where they may contribute to the repair progress. The present study aimed at evaluating the possible therapeutic effect of MSCs on induced colitis in albino rat. Methods and Results: Twenty male albino rats were divided into 3 groups (control, colitis, MSCs), control group (4 rats), colitis group (8 rats) received once intra-rectal injection of 2 ml of 3% acetic acid. MSCs therapy group (8 rats) injected with MSCs 24 hours after colitis induction. In each group, rats were subdivided into subgroups (a & b). Subgroup (a) corresponds to rats sacrificed 3 days and subgroup (b) corresponds to rats sacrificed 10 days after colitis induction. Isolation and culture of MSCs from rat bone marrow were performed. Colon sections were examined using light and fluorescent microscopy. Colon specimens were subjected to histological, morphometric and statistical studies. In colitis group, ulceration, loss of surface columnar epithelium, disturbed crypts architecture with few goblet cells and huge lymphatic nodule piercing the muscularis mucosa were reported. In stem cell therapy group, MSCs stimulate colonic repair through differentiation into several cells and dampen the inflammation. Conclusions: MSCs represent future therapeutic hopes for intestinal injury and chronic intestinal inflammatory states.