Background: The phrenic nerve (PN) transfer has been widely used in treating Brachial plexus avulsion injury (BPAI). But the present method overleaps the thoracic part of PN and nerve graft is needed, which leads to a long time of regeneration and partly irreversible muscle atrophy. We present our early experience of using Video-assisted-thoracic-surgery(VATS) to harvest a full-length of PN for transfer. Material and Methods: 15 patients (mean age 28) were treated. The thoracic part of PN was freed via VATS and taken out of the thoracic cavity, and full-length PN was transferred to the musculocutaneous nerve to recover the elbow flexion. The patients were followed up. Another 29 cases with long term follow-up who underwent traditional cervicle PN transfer to musculocutaneous nerve in our Institute between 1994 and 1997 were selected. The period of new-born potential appearing in biceps and the period for biceps to get M3 between two groups were compared. Results: The operation was safe and no complications occurred. The additional length of PN was 12.3°À4.5cm. 11 patients got sufficient follow-up. 8 patients got the biceps recover to M3 ( elbow flexion against gravity), mean time was 198.8°À36.0 days, much earlier than that of the traditional method (p<0.01). The pulmonary function recovered to pre-operation level 9 months after operation. Conclusion: This new method is safe and mini-invasive. The result of full-length PN transfer is much better than that of the traditional method. It shortens the time of nerve reinnervation obviously. It will offer a promising way for the patients had a long interval from injury to operation and for forearm muscles reconstruction by PN transferred to median nerve or combined with free muscle transfer.