Based on an anatomic study, a transfer of the brachialis muscle branch of the musculocutaneous nerve (BMBMCN) to finger flexor functional fascicles of the median nerve was designed. Preliminary results of clinical application of this new procedure are reported. Dissection of 32 cadaver upper limbs revealed that BMBMCN derives from the musculocutaneous nerve at the distal 1/3 upper arm level. Mostly it is of single-branch type, with an average dissectable length of 5.2 cm. At this level, functional fascicles of finger flexors are located at the posterior 1/3 of the median nerve. BMBMCN can be directly coapted to these finger flexion fascicles. In one case of brachial plexus lower trunk injury, this neurotization procedure was done. No impairment of elbow flexion and wrist flexion was found postoperatively. Recovery of finger and thumb flexion was seen 1 year postoperatively. This neurotization is safe and effective for treating lower trunk injuries. Copyright 2004 Wiley-Liss, Inc.