Ten premenopausal women with symptomatic uterine fibroids confirmed by magnetic resonance imaging (MRI) were treated with four injections (s.c.) of 3 mg of the gonadotrophin-releasing hormone (GnRH) antagonist cetrorelix every 4 days, starting on the first day of cycle. On every fourth day, blood samples were drawn for the measurement of gonadotrophins and sex steroids. On the 17th day of treatment after a final MRI control, myomectomy was performed laparotomically, laparoscopically or hysteroscopically. All patients showed a deep and sustained suppression of gonadotrophins and sex steroids over the treatment time. In three patients, no change or even an increase in uterine fibroids volume was observed according to MRI, and in one patient MRI did not allow a reliable interpretation. However, six patients showed a mean reduction of 31% in fibroid size after only 16 days of hormonal treatment. In nine patients laparoscopic or hysteroscopic myomectomy could be performed, while laparotomy was necessary only in one non-responder. Preparation of the cleavage plane during surgery was easy and blood loss was minimal. Patient compliance was excellent. No side-effects occurred. The GnRH antagonist Cetrotide(R), acting as an intermediate depot preparation at a dose of 3 mg, opens up a new avenue for preoperative short term treatment in a subgroup of patients with uterine fibroids, minimizing treatment time and patient discomfort.