Objective-To evaluate effects of transplantation of bone marrow stromal cells (BMSCs) into the CSF for the treatment of chronic spinal cord injury in dogs that had not responded by 1 month after decompressive surgery. Animals-23 dogs. Procedures-Dogs with paraplegia and loss of nociception in the pelvic limbs for at least 1 month after decompressive surgery were assigned to transplantation or control groups. Dogs in the transplantation group received BMSCs injected into the CSF 1 to 3 months after decompressive surgery. Dogs in the control group did not receive additional treatments. Improvements in gait, proprioceptive positioning, and nociception were evaluated by use of the Texas Spinal Cord Injury Scale for ≥ 6 months after BMSC transplantation. Results-6 of 10 dogs in the transplantation group regained the ability to walk, whereas only 2 of 13 dogs in the control group regained the ability to walk. Scores for the Texas Spinal Cord Injury Scale in the transplantation group were significantly higher than scores in the control group at the endpoint of the study (6 months after BMSC transplantation or after decompressive surgery for the transplantation and control groups, respectively). Only 1 dog (transplantation group) recovered nociception. All dogs from both groups had fecal and urinary incontinence. No complications were observed in relation to BMSC transplantation. Conclusions and Clinical Relevance-Injection of BMSCs into the CSF caused no complications and could have beneficial effects on pelvic limb locomotion in dogs with chronic spinal cord injuries.