OBJECTIVE: To compare the impact of expanded polytetrafluoroethylene (PTFE; Gore-Tex Surgical Membrane; W. L. Gore & Associates, Inc., Flagstaff, AZ) and oxidized regenerated cellulose (Interceed TC7, Johnson & Johnson Medical, Inc., Arlington, TX) on the development of postsurgical adhesions. DESIGN: A multicenter, nonblinded, randomized clinical trial. SETTING: University medical centers. INTERVENTIONS: Each barrier was allocated randomly to the left or right sidewall of every patient. PATIENTS: Thirty-two women with bilateral pelvic sidewall adhesions undergoing reconstructive surgery and second-look laparoscopy. MAIN OUTCOME MEASURES: Adhesion score (on a 0- to 11-point scale), the area of adhesion (cm2), and the likelihood of no adhesions. RESULTS: The use of both barriers was associated with a lower adhesion score and area of adhesion postoperatively. However, those sidewalls covered with PTFE had a significantly lower adhesion score (0.97 +/- 0.30 versus 4.76 +/- 0.61 points, mean +/- SEM) and area of adhesion (0.95 +/- 0.35 versus 3.25 +/- 0.62 cm2). Overall, more sidewalls covered with PTFE had no adhesions (21 versus 7) and, when adhesions were present on the contralateral sidewall, the number of sidewalls covered with PTFE without adhesions was greater than those covered with oxidized regenerated cellulose (16 versus 2). CONCLUSION: Expanded polytetrafluoroethylene was associated with fewer postsurgical adhesions to the pelvic sidewall than oxidized regenerated cellulose.