The musculocutaneous nerve has a short course and is deeply placed before piercing the coracobrachialis muscle at the point where it is relatively fixed by branches along its course between biceps brachii and brachialis muscles. Therefore, an isolated palsy of the musculocutaneous nerve is extremely rare and usually caused by stab, cut or bullet injuries. An isolated musculocutaneous nerve palsy, sparing the coracobrachialis muscle, can occur after heavy exercise of the arm musculature and has a good prognosis. We report a patient with an isolated musculocutaneous nerve palsy caused by motorcycle accident.