Twenty-eight (32.2%) subjects experienced severe or intractable pain within 1 h after the thermal balloon endometrial ablation procedure, while 26 (29.9%) subjects required morphine injection in the postoperative period. Overall, more than 70% of women experienced significant reduction in their menstrual flow. There was no difference in the clinical outcome between those who did or did not experience severe pain or between those who did or did not require morphine injection in the postoperative period.