Objective: To compare the effectiveness of two second-generation ablation techniques, bipolar radiofrequency impedance-controlled endometrial ablation and hydrothermablation, in the treatment of menorrhagia. Methods: This study was a double-blind, randomized controlled trial, which took place in a large teaching hospital in The Netherlands with 500 beds. Women with menorrhagia were randomly allocated to bipolar radiofrequency ablation (bipolar group) and hydrothermablation (hydrotherm group). At follow-up, both women and observers remained unaware of the type of treatment that had been performed. The primary outcome was amenorrhea. Secondary outcome measures were patient satisfaction and reintervention. Results: We included 160 women in the study, of which 82 were allocated to the bipolar group and 78 to the hydrotherm group. No complications occurred in either of the treatment groups. After 12 months, 87% (65 of 75) of the patients in the bipolar group were completely satisfied with the result of the treatment compared with 68% (48 of 71) in the hydrotherm group (relative risk 1.3, 95% confidence interval [CI] 1.03-1.6). The amenorrhea rates were 47% (35 of 75) in the bipolar group and 24% (17 of 71) in the hydrotherm group (relative risk 2.0, 95% CI 1.2-3.1). The relative risks for a reintervention in the bipolar group compared with the hydrotherm group was 0.29 (95% CI 0.12-0.67), whereas for hysterectomy, this was 0.49 (95% CI 0.15-1.5). Conclusion: In the treatment of menorrhagia, bipolar radiofrequency endometrial ablation system is superior to hydrothermablation.