PURPOSE: To evaluate clinical results of a single percutaneous injection of platelet-rich plasma in patients with refractory lateral epicondylitis. MATERIALS AND METHODS: Between Jan and Dec 2009, fifteen patients (5 male, 10 female) received a diagnosis of lateral epicondylitis of the elbow and were evaluated in this study. Their average age was 43.5 years. All patients were initially given a variety of non-surgical treatments for more than 1year. All patients were considering surgery. These patients were given a single percutaneous injection of 3cc of platelet-rich plasma. To assess pain, we used a visual analogue scale (VAS) at rest and during work & the Patient-Rated Tennis Elbow Evaluation (PRTEE) score. We compared the score before treatment with scores 4 and 12 weeks after treatment. RESULTS: Average VAS scores at rest improved from 4.6 before treatment to 2.5 at week 4, and 1.8 at week 12. The average VAS score while working also improved from 7.8 before treatment to 6.2 at week 4, and 4.25 at week 12. The average PRTEE score improved from 60.13 before treatment to 46.12 at week 4 and 24.6 at week 12. CONCLUSION: Treatment using a single percutaneous injection of platelet-rich plasma in patients with refractory lateral epicondylitis appears to be an effective treatment modality. Platelet-rich plasma should be considered before surgical intervention.