Abstract: ［Abstract］Objective　To compare the traditional electrophysiological testing with modified methods for differential diagnosis of Radial Tunnel Syndrome（RTS）. Methods　A total of 87 selected patients were initially diagnosed as Lateral Epicondylitis（LE） or Tennis Elbow （TE） by doctors from the Outpatient Department of Orthopedics and Rehabilitation. Medical history was asked. Patients received physical examination and examinations for the sensory nerve action potential（SNAP） of superficial radial nerve， the compound muscle action potential（CMAP） of radial nerve and needle electromyography（EMG）to record the muscle Motor Unit Action Potentials（MUAPs）. Then， the modified methods for CMAP of radial nerve were conducted on the forearm in the neutral，pronation and supination positions. Three values of CMAP latency were compared. RTS was diagnosed when the difference value≥0.3 ms. The χ2 test was used to compare the positive detectable rates of the two methods for the RTS diagnosis. Results　Thirteen out of 87 patients were diagnosed as RTS，among which three had interosseous nerve lesion and one had superficial radial nerve lesion. The traditional EMG failed to diagnose the remaining 9 RTS cases. These patients were finally diagnosed due to their latency difference of radial nerve CMAP ≥0.3ms when their forearms were examined in three positions. Conclusion　The modified electrophysiology method shows a higher positive rate for the diagnosis of RTS. （P＜0.05）.