Objective: To evaluate the efficacy of sclerotherapy for conservative treatment of ovarian pseudocyst. Methods: Patients with ovarian pseudocyst who had undergone sclerotherapy at Ajou University Hospital from February, 1997 to March, 2002 were included in this study. Sclerotherapy was performed as follows: Under intravenous analgesia, the cyst was irrigated with dehydrated alcohol after aspiration under transvaginal sonography. The aspirated contents and alcohol irrigated contents were sent for cytologic examination. Results: 71 patients with ovarian pseudocyst were performed sclerotherapy. All but 2 patients were followed up for 0.5 to 33 months with transvaginal sonography and pelvic examination. Mean age of the patients was 40 years old. Mean size of the pseudocyst was 8.0 cm, mean amount of aspiration fluid was 179.8 ml, and average follow-up duration was 6.0 months. All had abdominal or pelvic surgical history and 38 patients (58.9%) of them had undergone hysterectomy. 44 of 71 patients (62.0%) were performed sclerotherapy only one time. 27 patients (38.0%) recurred and were undergone more than one time. Complication was not occurred in all cases. Conclusions: We concluded that although pseudocyst after sclerotherapy has high recurrence rate, sclerotherapy was an safe and effective method for conservative treatment of ovarian pseudocyst.