To evaluate the effectiveness of Gonadotropin-Releasing Hormone analogue when administered preoperatively in hysteroscopic metroplasty.Prospective, comparative study.Sixty patients undergoing hysteroscopic metroplasty for septate uterus who were randomly allocated to pretreatment with two injections monthly of Gonadotropin-Releasing Hormone analogue or to no pretreatment. To assess the outcome of surgery three parameters were used: operative time (minutes), fluid adsorption (ml) and intraoperative bleeding.No significant differences in the operating time (21.9 vs 22.9 min), fluid adsorption (395 ml, range 200-550 vs 515 ml, range 250-650), intraoperative bleeding and failure rate were found between pretreated patients and controls.Preoperative treatment with Gonadotropin-Releasing Hormone analogue showed no advantage in hysteroscopic treatment of mullerian defects, but only an improvement, not statistically significant, in term of reduced operative time and fluid adsorption.