Tennis elbow is most often due to a tendinitis of the extensor carpi radialis brevis, and occasionally of the extensor digitorum. Pain felt at the outer aspect of the elbow, is elicited by grasping. Passive movements are painless, and of full range, excepted for extension, and varus strain tested in slight flexion. Isometric contraction of all the muscles controlling the joint are painless, excepted resisted extension of the wrist. The most usual painful spots lay on the lateral epicondyle, or lower on the common tendon. Diagnosis is confirmed when signs disappear immediately after a correct injection of lignocaine, and persist at least 3 Weeks if a corticoïd is added. The two outstanding differential diagnoses are internal derangement of the humero-radial joint, and entrapment of the sensory branch of the radial nerve. Many treatments are indicated. In a series of 58 cases, cervical manipulations give in most cases only a temporary relief; deep transverse massage applied on the tendon below the epicondyle, gives in a series of 131 cases good and excellent results in 63% of the cases. In a series of 257 cases, injections of corticoïds gives full relief in all cases, but the rate of recurrences is 66.7%, although 67% of those recur only once or twice. Percutaneous tenotomy performed only in patients recurring after temporary cure, drops the rate of recurrences to 13%. The last alternative is open surgery, releasing the common tendon.