OBJECTIVE: This study was performed to investigate the efficacy and safety of radiofrequency (RF) myolysis under transvaginal ultrasound guidance. METHODS: Transvaginal RF myolysis had been performed in one hundred nine women with uterine leiomyoma at Chung-Ang University hospital between Dec. 2004 and Mar. 2007. All patients, mean aged 42.8+/-5.8 years, desired their uterine conservation. Patients underwent physical examination, transvaginal pelvic ultrasound for measurement of the lesions preoperatively. Follow up was done at 1 week, 1 month, 3 months, 6 months after RF myolysis by same physician and measurement of size and volume of myoma and improvement of myoma specific symptoms such as menorrhagia and dysmenorrhea were checked at each visit. RESULTS: The mean maximal diameter of myomas treated by RF myolysis was 6.1+/-0.5 cm and average time of the procedure was 16.3+/-8.5 minutes. A significant decrease of myoma size and volume was observed at 1 month after myolysis. Mean reduction in maximal diameter was 29.9+/-4.8% at 1 week (p<0.001), 41.5+/-1.5% at 1 month (p=0.05), 46.2+/-3.9% at 3 months (p=0.003), 54.6+/-6.1% at 6 months (p<0.001) after RF myolysis respectively. Mean reduction in volume was 44.4+/-8.3% (p=0.001), 68.1+/-4.2% (p=0.035), 73.9+/-4.8% (p=0.042), 84.5+/-5.1% (p<0.001) at the same follow up period respectively. Significant improvement of symptom was observed at 3 months after RF myolysis. Transient low abdominal pain and prolonged vaginal bleeding were detected in 3 patients each but spontaneously resolved and no serious complication has been noticed or found. CONCLUSION: This study shows transvaginal RF myolysis could be a safe and effective method to treat uterine leiomyoma, allowing uterine conservation with significant volume reduction and rapid return to normal activity.