Nerve transfer procedures are increasingly performed for repair of severe brachial plexus injury (BPI), in which the proximal spinal nerve roots have been avulsed from the spinal cord. The procedure essentially involves the coaption of a proximal foreign nerve to the distal denervated nerve to reinnervate the latter by the donated axons. Cortical plasticity appears to play an important physiological role in the functional recovery of the reinnervated muscles. The author describes the general principles governing the successful use of nerve transfers. One major goal of this literature review is to provide a comprehensive survey on the numerous intra- and extraplexal nerves that have been used in transfer procedures to repair the brachial plexus. Thus, an emphasis on clinical outcomes is provided throughout. The second major goal is to discuss the role of candidate nerves for transfers in the surgical management of the common severe brachial plexus problems encountered clinically. It is hoped that this review will provide the treating surgeon with an updated list, indications, and expected outcomes involving nerve transfer operations for severe BPIs.