We performed this study to assess the feasibility and effectiveness of ultrasound-guided drainage and ethanol instillation for the treatment of pelvic peritoneal cysts. Six women had pelvic peritoneal cysts after previous pelvic surgery; when the cysts recurred after simple drainage, the patients underwent transvaginal ultrasound-guided drainage and instillation of 20-30 mL of ethanol into the cyst cavity. All patients except one presented with abdominal pain. All cysts had clinical and ultrasonic benign characteristics. Drainage and ethanol instillation were performed successfully in all patients without severe side effects or complications. After a mean follow-up time of 13.6 months, a recurrence was found in only one patient, who was successfully retreated. These preliminary results indicate that transvaginal ultrasound-guided fluid drainage and ethanol instillation is an effective treatment for pelvic peritoneal cysts.