OBJECTIVE To study whether intraspinally transplanted human cord blood CD34+ cells can survive, differentiate, and improve neurological functional recovery after spinal cord injury in rats. METHODS Rats were randomly divided into two groups. One group of rats was subjected to spinal cord left-hemisection and transplanted with human cord blood CD34+ cells labeled by bromodeoxyuridine (BrdU); The other group was carried by left-hemisection with injection of PBS (control group). The neurological function was determined before and 24 h, 1, 2, 3 and 4 weeks after spinal cord injury and cell transplantation using the modified Tarlov score. The distribution and differentiation of transplanted human cord blood cells in vivo in rat spinal cord were evaluated by histological and immnuhistochemical analysis. RESULTS Functional recovery determined by modified Tarlov score was significantly improved in the group receiving human cord blood CD34+ cells compared with the control group (P < 0.05). Moreover, human cord blood CD34+ cells were found to survive in rat spinal cord microenvironment, with the expression of the neural nuclear specific protein (NeuN) in 2% BrdU-reactive human cells and of the astrocytic specific protein glial fibrillary acidic protein (GFAP) in 7% BrdU-reactive human cells. CONCLUSIONS Intraspinally administered human cord blood CD34+ cells can survive, differentiate, and improve functional recovery after spinal cord injury in rats. Transplantation of human cord blood cells may provide a novel strategy for the treatment of neural injury.