Objective To evaluate the clinical effect of surgical operation for recovering the function of ulnar nerve with large segment defect. Methods Twentycases with the large segment defect of ulnar nerve were retrospectively analyzed from September 1999 to December 2006 in the hospital.All the patients were treated by the operation of nerve end-to-side neurorrhaphy . The broken end of ulnar nerve was anastomosed with the median nerve. And observed the recovery of the sensation and motion function of the little finger, interosseous muscles and claw hand, then compared with before. Results All cases were followed up for 8 to 36 months. The mean was 16 months. The sensation and motion function of the little fingers had better restoration after operation. No incision infection, anchylosis or myatrophy was occurred.Excellent(M4 + S4 +) ,Good (M3S3), moderate (M2S2), and poor effects (M1S1) were achieved respectively in 6, 4,2 and 0 cases based on the scale of XU' s grading standard.The excellent and good rate was 83.3%. Conclusion The nerve end-to-side neurorrhaphy was a effective treatment for the patients with large segment defect of ulnar nerve.