OBJECTIVE To evaluate the long-term effects on the lower limb function after S nerve root transection as dynamic source. METHODS Between January 2007 and December 2011, 47 patients with atonic bladder dysfunction underwent S1 nerve root transposition to reconstrut the bladder function. There were 43 males and 4 females, with an average age of 40.7 years (range, 22-66 years). The locations were L1 in 33 cases, L2 in 5 cases, L3 in 2 cases, T12, L, in 3 cases, L1, L2 in 1 case, L1, L3in 1 case, L1, L4 in 1 case, and L2, L3 in 1 case. The anastomosis of the S2 or S3 nerve root to S1 nerve root was performed from 4 to 24 months (mean, 8 months) after spinal cord injury. The strength of ande plantar flexion was grade 4 in 5 cases and grade 5 in 42 cases before operation. RESULTS The strength of ande plantar flexion had no obvious decrease (grade 4 or 5) in 31 cases, reduced 0.5 grade in 16 cases at 2 days after operation. All the patients were followed up 3-8 years (mean, 5.1 years). At 2 weeks after operation, the nerve electrophysiological examination showed neurogenic damage at operated side in most patients, including reduced amplitude tibial nerve in 19 cases, for common peroneal nerve in 13 cases, and for tibial nerve and common peroneal nerve in 9 cases. Except the velocity of common peroneal nerve (t = -1.881, P = 0.093), the other electric physiological indexes showed significant differences between at pre- and post-operation (P < 0.05). The muscle strength basically recovered to preoperative level (grade 4 or 5) during follow-up, and there was no impairment of lower limb function. CONCLUSION S1 transection has no significant effects on lower limb function, so S1 nerve can be used as dynamic nerve for nerve function reconstruction.