Tennis elbow, also known as lateral epicondylitis, is the inflammatory status of insertion site of common extensor tendon to humerus. It is usually related to overuse of local muscle. Radial extracorporeal shock wave therapy (rESWT) is a non-invasive physical treatment. It applies shockwave energy to the lesion site, enhancing the growth of microvascularity, inducing tissue repair, and thus relieving the symptom.