Dissections of 20 antebrachial specimens were done to define the location of the proximal lateral antebrachial cutaneous nerve, which is the distal sensory extension of the musculocutaneous nerve. Our findings varied from those noted in most anatomic and surgical texts in that the nerve emerges from the lateral aspect of the biceps tendon at the level of the interepicondylar line. At the point defined, the distribution of the nerve in ten volunteers was successfully anesthetized with 1.5 ml of 1% lidocaine. The accurate anatomic localization of this nerve should be of interest to surgeons and anesthesiologists in supplementing failed axillary blockade, in diagnosing and treating the musculocutaneous impingement syndrome, in harvesting the proximal nerve for diagnostic tests or donor graft purposes, and in differentiating the sensory distribution of this nerve from that of the radial nerve.