OBJECTIVE: To verify the rationality, reliabilit y and practicability of selective transfer of ipsilateral C(7) nerve root for tr eatment of upper trunk avulsion. METHODS: Selective transfer of ipsilateral C(7) nerve root was ca rried out in 8 patients (7 with upper trunk avulsion, and 1 with left upper trun k avulsion combined with partial injury of the middle trunk) from June 1996 to F ebruary 1997. Selective transfer of the anterior division or the anteriolateral fascicles of the anterior division of ipsilateral C(7) to the anterior division of the upper trunk was performed under general anesthesia. Only 5 cases were fol lowed up. RESULTS: Among these 5 cases, effective recovery was observed o n 4 cases of the transfer of the anteriolateral fascicles of ipsilateral C(7) to the anterior division of the upper trunk. Electromyographic examination showed nerve regeneration could be observed in the 2nd month postoperatively. And detec table elbow flexion by biceps contraction was found in the 4th month postoperati vely. The function of the C(7) innervating muscles was not jeopardized, and the case with combined partial C(7) root injury had a poor result. CONCLUSIONS: Selective transfer of ipsilateral C(7) nerve root leads to a restoration of reinnervating muscle functions without affecting the f unction of the muscles innervated by C(7). It is therefore a practicable new sur gical procedure for treating upper trunk avulsions.