Objective — to develop and assess criteria for the efficiency of microwave endometrial ablation (MAE) in premenopausal patients with abnormal uterine bleeding (AUB), by using up-to-date diagnostic techniques. Subject and methods. Sixty-two premenopausal patients aged 46—55 years with AUB were examined. Hysteroscopy and separate diagnostic curettage of the uterine mucosa were performed in all the patients before and after MEA in its different periods on admission to hospital and for prior AUB. Endometrial polyps or hyperplasia were detected in 59 patients; atypical endometrial hyperplasia was present in 3. Control hysteroscopy after MAE revealed adequate debridement of the uterine wall in 42 patients; additional insertion of an applicator and targeted cauterization of undebrided endometrial areas were done in 20. Two- and three-dimensional ultrasound echography within 15 months of follow-up could trace changes in the uterine cavity, as well as stages of Asherman’s syndrome. Results. A complete or incomplete clinical effect after MAE was observed in 50 (80%) and 8 patients, respectively; no effect was stated in 4 patients. None or incomplete effect was found in patients with AUB concurrent with existing adenomyosis. Conclusion. MAE is a safe and feasible method to treat remenopausal patients with an endometrial hyperplastic process. Prior to MAE, it is appropriate to carry out hysteroscopy and separate diagnostic curettage of the uterine mucosa if there are endometrial pathological changes. The criteria for the efficiency of MAE are as follows: no genital tract bleeding; thin M-echo (less than 4 mm) or the registration of the development of Asherman’s syndrome; no blood flow in the radial and basal arteries of the uterus at color Doppler mapping.