Background/Aim: Traditionally endometrial hyperplasias have been treated with progestins. Unfortunately, quite often hyperplasias are resistant to treatment, or they recur after therapy. The aim of the study was to compare traditional progestin administration with thermal balloon endometrial ablation in the treatment of non-atypic endometrial hyperplasia. Methods: Women with endometrial hyperplasia (n = 34) were randomized in a 1:1 allocation ratio. Endometrial biopsy samples were taken 6 and 12 months after the treatment; if any signs of hyperplasia were detected, hysterectomy was performed. In addition, the hospital records were checked in September 2003 to observe for any later hysterectomy. Main outcome measures wererecovery from hyperplasia and avoidance of hysterectomy. Results: In patients treated with thermal ablation, the hyperplasias persisted at 6 or 12 months in 4 out of 17 patients, whereas the rate was 6 out of 17 patients in the progestin therapy group. According to patient records, 1 further patient treated with thermal ablation and 3 further patients treated with progestin were hysterectomized after the last visit. A total of 14 of the 34 patients (41%) have been hysterectomized so far. Conclusions: These preliminary results suggest that thermal balloon endometrial ablation therapy seems to be as effective as traditional progestin administration in the treatment of non-atypic endometrial hyperplasia. The hysterectomy rate during the follow-up period was, however, considerably high, and, therefore, hysterectomy might be considered even a first-choice treatment for endometrial hyperplasias.