Objective: To evaluate the feasibility of the hysteroscopic resection of type II submucous fibroids regardless of the myometrial free margin separating them from the serosa and to report the dynamic changes the margin undergoes after the various phases of resection. Design: A prospective observational study. Setting: A tertiary-level university hospital. Patient(s): Thirteen women with single type II submucous fibroids of ≤5 cm in diameter regardless of the myometrial free margin. Intervention(s): Hysteroscopic myomectomy and ultrasound evaluation of myometrial free margin before and after each phase of the procedure. Main Outcome Measure(s): The possibility of a complete one-step resection, the incidence of intraoperative or postoperative complications, and the analysis of the dynamic changes occurring in myometrial free margin. Result(s): Complete resection was performed successfully in all patients. No complications were registered. The myometrial free margin decreased on the distension of the uterine cavity and then increased progressively and significantly after the various phases of resection. Conclusion(s): In selected cases and in experienced hands, hysteroscopic myomectomy of type II submucous fibroids may be performed successfully and safely regardless of the myometrial free margin. Myometrial free margin increases progressively with each step of the procedure probably leading to an increasing margin of safety. Copyright © 2011 American Society for Reproductive Medicine, Published by Elsevier Inc.