Purpose: One of the factors suggested to be causative in hernia formation is defective collagen metabolism. In this study, we investigated whether there is any relationship between the collagen contents of indirect hernial sacs and certain demographic and anatomic parameters. Methods: Hernial sac hydroxyproline levels were measured in 100 pediatric and 23 adult indirect inguinal hernia cases as indicators of collagen concentrations. Hydroxyproline levels were compared between boys and girls, right and left sided hernias, unilateral and bilateral cases, children and adults. Whether there was any relationship between patient age and hydroxyproline level was also investigated. Results: No difference was found between males and females (p > 0.05), right and left sided hernias (p > 0.05) or unilateral and bilateral cases (p > 0.05). Hydroxyproline levels of adults were found to be significantly higher than those of children (p = 0.000). There was also a positive correlation between age and hydroxyproline levels of boys (r = 0.285, p = 0.023). Conclusion: Although a relationship between direct inguinal hernia and collagen structure has been shown by some investigators, we were unable to point to any significant findings which would indicate such a relationship in indirect inguinal hernia cases. Further studies on hydroxyproline levels in peritoneal samples will be necessary to understand the role of peritoneal hydroxyproline levels in hernia formation.