We performed a prospective cohort study comparing TCRE and hot-fluid balloon ablation in consecutive patients suffering from menorrhagia and not responding to medical treatment. Between 1992 and 1994, all patients had TCRE, whereas from 1995 onward, all patients had balloon therapy. Outcome measures were surgical reintervention, menstrual pattern, and patient satisfaction. Assuming a 9% reintervention rate after TCRE, a series of 150 patients was required to show balloon ablation to be equally effective.