Fifty cases in 48 patients of intractable medial tennis elbow tendinosis (medial humeral epicondylitis) were treated surgically from 1985 to 1990 with identification and excision of the injured tendon, while retaining and closing the resection defect. All patients had symptoms that were aggravated by repetitive upper extremity activities and had failed to improve with nonoperative therapy. At surgery, the flexor carpi radialis-pronator teres interval was involved in 28 cases. Histologic examination revealed angiofibroblastic tendinosis and fibrillary degeneration of collagen. Postoperative followup averaged 37 months. An analog scale was used to analyze pain intensity, and pain occurrence was evaluated by a pain phase scale. All patients reported partial or complete pain relief postoperatively (improvement in their pain phase and pain intensity scales). Preoperatively, 14 patients had pain at rest; all 14 had relief of this pain postoperatively. Ten patients did not return to their sporting or occupational activities. Objective dynamometer strength testing revealed a significant improvement postoperatively in all patients; no major complications were seen in this series. A large percentage of patients who fail conservative treatment for medial humeral epicondylitis (tendinosis) can obtain pain relief and return to activities with the described operative technique.