Objectives: To assess the effectiveness of peripheral nerve blocks with phenol, and also to determine the duration of spasticity in patients with spinal cord injury. Subjects: 36 spinal cord injured patients with serious spastic lower limb treated at Rehabilitation Center, Bach Mai Hospital. Methodology: Longitudinal follow-up, compare Ashworth scale before and after 5 percent phenol injection (1 week, 1 month, 2 month). Results: Fifty peripheral nerve blockages were carried out. The peripheral nerves selected were as follows: 34 obturator nerves, 11 sciatic nerves, and 5 femoral nerves. Degrees of (1) and (1 +) were taken to be acceptable. One patient developed cutaneous anaesthesia after injection but it, vanished by the three week. Conclusion: Peripheral nerve block by phenol 5 percent well acting with lower limbs to the spinal cord injury patients in certain durations but not in long time.