Objective: To study the uterine cavity after thermal endometrial destruction for the treatment of menorrhagia by means of a balloon catheter, the CavatermTM system. To relate the appearance of the uterine cavity to the outcome of the treatment. Methods: Fifty-one of the first 60 women treated with balloon endometrial destruction were examined with hysteroscopy and saline infusion sonography 11–28 months after treatment. Results: Patients with minimal or no bleeding after thermal endometrial destruction had more uterine fibrosis than patients bleeding more. Conclusion: The greater the degree of fibrosis of the uterine cavity after balloon endometrial destruction by thermal coagulation, the better the effect on menorrhagia.