: ObjectiveTo establish whether the concentration of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), and transforming growth factor-beta (TGF-β) is influenced by the presence or absence of adhesions, and whether the concentration of these mediators vary throughout the menstrual cycle.: DesignProspective case-control study.: SettingWomen undergoing laparoscopy in a university hospital in the United Kingdom.: Patient(s)Women undergoing laparoscopy for benign gynecological conditions.: Intervention(s)Samples of peritoneal fluid were collected at diagnostic laparoscopy in one group, and at laparoscopy and serially during the first 48 hours after laparoscopic adhesiolysis in a second group. We correlated the concentrations of mediators in serially sampled peritoneal fluid during the 48 hours following laparoscopic adhesiolysis to the adhesion formation and reformation found during second-look laparoscopy.: Main outcome measure(s)The concentrations of MMP-9, TIMP-1, and TGF-β in peritoneal fluid.: Result(s)MMP-9 concentration was lower in the follicular phase than the luteal phase of the menstrual cycle. MMP-9 concentration was significantly lower in women with pelvic adhesions than in women with a normal pelvis. The MMP-9/TIMP-1 ratio is significantly higher in women with significant adhesions at second-look laparoscopy compared to women with minimal or no adhesions.: Conclusion(s)The components of extracellular matrix remodeling may play an important part in the adhesion formation/reformation process. [Copyright &y& Elsevier]