Objective: To evaluate the effectiveness of hysteroscopic endometrial ablation in women with abnormal benign uterine bleeding resistant to clinical treatment, and to identify factors potentially related to its failure. Methods: Ninety patients with abnormal benign uterine bleeding were retrospectively evaluated. They were submitted to endometrial ablation between January 2000 and August 2003. Their mean age was 44.3 years and their average parity was 2.3 childbirths. All patients had been given gonadotrophin-releasing hormone analogues prior to surgery, to make the procedure easier. Rresults: After surgery, amenorrhea occurred in 20% of cases, hypomenorrhea in 30%, and eumenorrhea in 32.2%. In 17.8% of patients, the procedure failed. No intra or postoperative complications occurred. There was no statistically significant difference between the patients in which the ablation failed and those in which it was successful regarding mean age (p = 0.557), parity (p = 0.891), presence of intramural myoma (p= 0.29), submucosal myoma (p = 0.68) or endometrial polyps (p = 0.76). A significant difference between the two groups was observed with regard to the uterine size median (7  cm in the successful group and 9 cm in the failure group, p  = 0.008). A statistically significant difference was also found in follow-up time: 13 months in the first group and nine months in the second group (p = 0.001). Cconclusions: Endometrial ablation is a good treatment method for abnormal uterine bleeding of benign etiology. Special attention must be paid to patients with increased uterine size, since failure is more frequent in these cases.