The aim of this study was to evaluate uterine adhesions after myomectomy and peritoneal fibrinolytic capacity in women treated with gonadotrophin-releasing hormone agonist (GnRHa) before surgery. A prospective observational study comprised 15 infertile women who underwent myomectomy. Before surgery, 10 were treated with buserelin acetate (900 microg/day) for 10-12 weeks followed by additional postoperative treatment with GnRHa for 4 weeks (GnRHa group) and five received no treatment (control group). Peritoneal fluid specimens were taken at the beginning of myomectomy and the adhesions were estimated by second-look surgery (caesarean section or laparoscopy). Levels of plasminogen activator (PA) and PA inhibitor (PAI) were determined by enzyme-immunosorbent assays. Pre- and postoperative GnRHa therapy significantly reduced adhesion formation compared with control groups (adhesion scores; 0.2 +/- 0.4 vs. 2 +/- 1, P<0.0001). GnRHa group showed a significant decrease in PAI level (P<0.0001) but no significant change in PA level, suggesting increased fibrinolytic capacity in peritoneal fluid from GnRHa-treated patients. These data suggest that GnRHa therapy is successful in preventing adhesion formation after myomectomy. GnRHa-induced shift to more fibrinolytic activity, mainly because of a decreased level of PAI, may play a critical role in the mechanism of the GnRHa's action on postoperative adhesion development.