Objective: The phrenic nerve and the contralateral seventh cervical (C7) nerve root are the most commonly used donor nerves in the treatment of total brachial plexus avulsion. The aim of this study was to determine if the phrenic nerve or the contralateral C7 nerve root yields a superior outcome for nerve transfer. Methods: A total of 60 Sprague-Dawley rats were randomly assigned to 1 of 3 groups. In Group A the phrenic nerve was used as the donor nerve; in Group B the contralateral C7 nerve root nerve was used as the donor nerve; in Group C the nerve was directly sutured. The results of behavioral assessment, electrophysiology, histology, nerve fiber count and muscle weight at 24 weeks postoperatively were recorded. Results: Group A showed a faster recovery time compared to Group B; however Group B showed a better functional recovery at the final outcome assessment compared to Group A. Conclusion: The contralateral C7 nerve root was better as the donor nerve for nerve transfer in the treatment of total brachial plexus avulsion.