Objective: To assess the expression of integrin alphav and beta3 in the serosal tissue of intraperitoneal organs and adhesions in persons with and without adhesions. Design: Prospective study. Setting: Academic research centers. Patient(s): Fifiy-seven patients undergoing abdominal or pelvic surgery. Main Outcome Measure(s): Integrin alphav and beta3 messenger RNA (mRNA) expression was evaluated by quantitative reverse transcription polymerase chain reaction. Result(s): The serosal tissue of the parietal peritoneum, uterus, fallopian tubes, ovary, and the large and small bowel, as well as peritoneal adhesions, skin, fascia, subcutaneous tissue, and omentum, expresses integrin alphav and beta3 mRNA. The level of alphav and beta3 mRNA expression varied among these tissues; expression of the former substance was highest in uterine serosa and lowest in the skin and small bowel, and expnssion of the latter substance: was highest in the fallopian tubes and skin and lowest in the uterine serosa. Parietal peritoneum and adhesions express equal levels of integrin alphav; however, integrin beta3 expression was >100-fold lower in adhesions than in peritoneum. The level of integrin beta3 expression in omentum, small and large bowels, and subcutaneous tissue was 100-fold to 10,000-fold lower than in other tissues. Conclusion(s): Serosal tissue of peritoneal organs and adhesions express variable levels of integrin alphav and beta3 mRNA. On the basis of such variation and the knowledge that tissue injury alters local integrin expression, integrins may play a key role in adhesion development, particularly in tissue with higher integrin expression. (Fertil Steril (R) 2001;75:791-6. (C) 2001 by American Society for Reproductive Medicine.).