BACKGROUND The aim of the study was investigating the influence of Schwann cells-alginic acid sodium hydrogel co-transplantation on a rat model of spinal cord injury. METHODS Sprague-Dawley (SD) rats were randomly assigned to 4 groups: control, injury, injury with Schwann cell transplantation, and injury with Schwann cells-alginic acid sodium hydrogel co-transplantation. Gelatin sponge blocks containing a Schwann cell suspension were transplanted into the injury site in the Schwann cell group; Schwann cells seeded in alginic acid sodium hydrogel were transplanted into the injury site in the Schwann cells-alginic acid sodium hydrogel group. At 12 h, 1, 3, 7, and 21 days after surgery, animals were assessed on the Basso, Beattie and Bresnahan (BBB) locomotor rating scale and then were sacrificed. RESULTS In the injury group, Bcl-2 immunoreactive cells peaked at 3 days after surgery, and the expression level returned to normal level at 14 days. In the co-transplantation group, Bcl-2 immunoreactive cells in the spinal cord-transected segments were significantly increased until 7 days (p < 0.05) and remained at this level for more than 14 days. In the injury group, the number of apoptotic cells was the highest, as compared with the other 3 groups, and peaked at 1 and 7 days following spinal cord injury, and they were mostly distributed in the white matter. The BBB scores were significantly higher in the Schwann cells-alginic acid sodium hydrogel transplantation group than in the simple injury and Schwann cell groups (p < 0.05). CONCLUSIONS Schwann cells-alginic acid sodium hydrogel co-transplantation could inhibit cellular apoptosis and enhance Bcl-2 expression in the spinal cord-transected segments, and thereby promote the recovery of locomotor function after spinal cord injury, although it did not reach full rehabilitation.