To determine whether pre-operative treatment with gonadotrophin-releasing hormone (GnRH) analogue may have a beneficial effect on surgery outcome, 53 patients with symptomatic fibroid uteri awaiting myomectomy or transabdominal hysterectomy (TAH), were randomly divided into a study group (n = 29) and a control group (n = 24). The study group of patients were treated by an i.m. injection of D-Trp6 LHRH microcapsules at 2 months and 1 month prior to surgery. The control group had no pre-operative treatment. Haemoglobin concentration and oestradiol, follicle-stimulating hormone and luteinizing hormone concentrations were measured at 2 months and 1 month prior to surgery, and at surgery. The duration of surgery was shorter in the study group (49 versus 70 min in the hysterectomy group) and intra-operative blood loss was less (208 versus 309 ml in the hysterectomies and 320 versus 476 ml in the myomectomies). Pre-operative treatment with GnRH-agonists which induces shrinkage of the uterus and fibroids is therefore efficient in shortening the duration of surgery, and diminishing the intra-operative blood loss in surgery for fibroid uteri. Such preoperative treatment is therefore a useful addition to surgery in cases with symptomatic fibroid uteri.