External urethral sphincter hypertonicity(EUSH) with or without detrusor hyperreflexia has been known as the most common cause of unbalanced neurogenic bladder in patients with spinal cord injury. Antispastic drugs or muscle relaxants have been tried to treat EUSH. However, the drugs to treat EUSH required too large dose and long-term treatment, with side effects. We performed 15 pudendal nerve blocks using 7% phenol solution in 8 patients who were not effective on relaxation of external urethral sphincter with large residual urine(150ml to 600ml) despite of 80 mg baclofen and 20 mg diazepam a day and intermittent catheterization over minimal 3 weeks. Drugs were discontinued at least for 48 hours. The neurological deficit was complete in 3 paraplegics and incomplete in 5 (2 paraplegics and 3 quadriplegics). Patient age ranged from 24 to 58 years, with mean age of 42.6 years. The recording of residual urine were done before and after pudendal nerve blocks. A pudendal block was produced by injecting 7% phenol solution with specific localization of the nerve by electrical stimulation into the area medial to the ischial tuberosity. Voiding patterns have been markedly improved and the residual urine had dropped. Of the 8 patients who underwent pudendal block, 5 had excellent results, and 1 good and 1 fair result. There has been no impairment to urinary continence. The mean difference of 255.7ml of the residual urine before and after pudendal nerve block in 7 patients, with exclusion of one patient having urethral stricture, was highly significant statistically(p<0.001).