Objective:To investigate the effects of intra-spleen injection with immature dendritic cells on donor-specific tolerance in rats receiving intestinal transplantation. Methods:DCs were collected from bone marrow progenitor cells of rats cultured with GM-CSF in vitro. The DCs were harvested after six-day culture and the expression of co-stimulation molecular and MHC-Ⅱwas detected. Severn days before transplantation of small intestinal from F344 donors, donor-derived DCs(2 × 106) were injected into either the peripheral vein(group C) or the spleen(group D). Normal saline was injected through either the peripheral vein(group A) or the spleen(group B) before transplantation. Small intestinal transplantation was performed and the survival rate of recipients was observed. Histological examination was done and apoptosis death of infiltrating cells in allografts was analyzed. Results:The survival of recipients in group D was(17.50 ± 1.05)days, which was significantly longer than that in group A[(7.17 ± 1.17)days],B[(7.33 ± 1.51)days] and C[(12.83 ± 2.79)days] respectively(P < 0.05). The degree of the inflammatory infiltrated cells and intestinal mucosa structural injury of mucosa in group D were alleviated significantly compared with that in group A,B and C. Conclusion:The intra-spleen injection of modified immature dendritic cells can induce immune tolerance and prolong the survival of rat small bowel allografts.