Twenty one cases of birth palsy of the brachial plexus have been explored surgically. The patients were aged from seven weeks to nine years. The results of pre-operative examination are described and myelography is considered to be especially important. It was found that ruptures of the upper roots at the junction of C5-C6 were frequent and could be repaired by nerve graft. Avulsion from the spinal cord was more frequent in the lower roots. It is concluded that surgical exploration and attempted repair should be done early, preferably at the age of two or three months in cases of absence of spontaneous recovery.