OBJECTIVE: To evaluate the effect of extracorporeal shock wave therapy (ESWT) and the improvement of ultrasonographic findings in refractory chronic epicondylitis of the elbow. METHOD: Twenty seven patients (7 men, 20 women, mean age 47) with minimum 1 year history of chronic epicondylitis of the elbow that was unresponsive to conventional therapy were included. Each patient was treated with 3~4 sessions of low-energy (0.06~0.12 mJ/mm2, 2000 impulses) ESWT. A 100-point scoring system, Nirschl score and Roles and Maudsley score were evaluated before treatment and at the 3- and 6-month follow-up. Ultrasonography was performed before treatment and at the 3-month follow-up. RESULTS: Total score of a 100-point scoring system and Nirschl score were significantly improved at the 3- and 6-month follow-up compared to before treatment (p<0.05). Follow up ultrasonography was performed in twenty one patients. Eighteen of 21 patients (85.7%) showed improvement of tendinosis and 4 of 6 patients (66.7%) showed improvement of tear and 3 of 10 patients (30.0%) showed improvement of calcification on ultrasonography. CONCLUSION: ESWT is safe and effective modality in the treatment of refractory chronic epicondylitis of the elbow. And ultrasonography can be a useful method to evaluate the therapeutic effect of ESWT.