A case is reported of high radial nerve palsy in an elite bodybuilder caused by an extrinsic mass effect of muscular hypertrophy. Surgical decompression resulted in complete clinical resolution. P eripheral compressive neuropathies of the arm are common, and a thorough understanding of the anatomy, pathophysiology, and clinical correlation are required for diagnosis and prognosis. Nerve compressions may be acute or chronic, and may remain mild or result in considerable disability, depending on the mechanism of the injury and the extent of the insult to the nerve. The latter also dictates the prognosis of nerve recovery.We report a unique case of high radial nerve palsy in an elite bodybuilder caused by an extrinsic mass effect of muscular hypertrophy, with complete clinical resolution after surgical decompression. We believe that this is the first report of such an injury in a bodybuilder. CASE REPORTA 45 year old, right handed, elite, male bodybuilder presented with a two week history of gradual onset of spontaneous right wrist drop. There was no evidence of recent trauma to the brachial plexus, upper arm, or forearm to account for the condition. Past medical history included left sided carpal tunnel syndrome, which resolved spontaneously in six months. Physical examination showed considerable wasting of the brachioradialis muscle, loss of the extensor carpi radialis and extensor carpi ulnaris, loss of digital extensors, and loss of the extensor pollicis longus and abductor pollicis longus. The triceps were preserved clinically. Plain radiography did not show any sinister bony and soft tissue lesion. A nerve conduction study showed severe acute motor denervation of muscles innervated by the right radial nerve, suggesting a lesion around the spiral groove. In view of spontaneous recovery of a previous compressive neuropathy without surgical intervention, a similar approach of conservative treatment was started with non-steroid anti-inflammatory drugs and physiotherapy. He was reviewed again after three months; no improvement was found. Magnetic resonance imaging of the right arm did not show any abnormal soft tissue mass, with a normal appearance of the humeral cortex and marrow signal. As no recovery was noted after four months, exploration of the right radial nerve was planned. The patient was placed in the lateral decubitus position, and a posterior longitudinal incision ( fig 1) was made. The radial nerve was identified after entering the interval between the long and lateral heads of the triceps. The raphe was incised in the usual manner to expose the nerve. The course of the nerve was traced proximally. There was a notable extensive venous engorgement of the comitantes vessels. The nerve was dissected proximally to the inferior edge of the teres major, which appeared to be constricting the underlying nerve. The aponeurotic edge of the muscle was incised 1.5 cm proximally allowing free passage of the examining digit into the triangular space until no extrinsic compression