This is a case report.Anconeus is a small, triangular muscle in the posterior aspect of the elbow, and it functions as weak elbow extensor and abducts the ulna during pronation. The contribution of anconeus muscle can cause lateral elbow pain, which is difficult to diagnose and treat. It also does not respond to the regular treatment for lateral epicondylitis.The purpose of this study was to report anconeus muscle irritation as a sole cause for lateral elbow pain.The patient was given an elbow splint for 4-6 weeks followed with eccentric and concentric strengthening to the elbow and wrist.At the end of week 9, the patient was pain-free.The clients who are not responding with the usual treatment of lateral epicondylitis should be considered for any anconeus involvement.