Objective: To compare the effects of low-dose oral contraceptives used alone and in combination with a gonadotropin-releasing hormone (GnRH) analog to treat heavy menstrual bleeding. Methods: Fifty-eight patients with heavy menstrual bleeding were prospectively randomized into two treatment groups to receive either a low-dose oral contraceptive alone (group 1), or combined with a GnRH analog (group 2) for 6 months. The patients' hormonal profiles, and hemoglobin and hematocrit levels were measured at the beginning and at the end of the treatment period. Results: Hemoglobin and hematocrit levels significantly improved in both groups after 6 months of treatment (P<0.05 and P<0.01, respectively). Even in the first month of the study, the number of pads used and the duration of menstruation were significantly decreased in both groups and markedly lower in group 2 (P<0.01). Conclusion: The addition of a GnRH analog to low-dose oral contraceptive treatment for heavy menstrual bleeding resulted in better control of vaginal bleeding, even in the first month of therapy. (C) 2008 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.