Restoration of elbow flexion is a major objective in the treatment of brachial plexus palsies affecting the upper roots. The “Ulnar-Biceps Median-Brachialis” (the so-called UBMB) double nerve transfer described by Oberlin became a standard procedure in C5–C6 and C5–C6–C7 injuries. Motor fasciculi of the ulnar and median nerves dedicated to wrist flexors are transferred onto branches from the musculocutaneous nerve, aiming at the biceps and the brachialis muscles, respectively. Perioperative nerve stimulation is essential for choosing the appropriate donor branches, in order to spare the priority functions of the hand.