Objective To study the effects of bone marrow mesenchymal stem cells transplantation on functional recovery of the injured rats spinal cord.Methods MSCs labeled with Brdu were transplanted into rats model of spinal cord half-transection injury.The open-field BBB scoring system was employed to evaluate behavioral changes.MSCs' survival after transplantation was identified by BrdU immunohisto chemistry.We observed the reconstruction of neuronal circuits by HRP coloration.The recovery of transduction function after spinal injury was examined by cortex somatosensory evoked potential (CSEP).Results Treated rats generally showed better functional recovery than control rats after operation.BrdU-positive cells could be found in the spinal cord injury site one week after transplantation.At two months after transplantation, HRP-positive cells could be found at rostral of the spinal cord injury site of treated rats, but not be found in control.CSEP could be evoked at treated rats from two months after transplantation,but not in controls.Conclusion MSCs may survive in the spinal cord injury site via local injection immediately after spinal cord injury, and may promote regeneration of the injured axons.