Background: We aimed to evaluate the effect of different capnoperitoneum pressures on stress responses in pediatric laparoscopic inguinal hernia repair.Methods: In this prospective randomized controlled study, 68 children with indirect inguinal hernia who underwent high ligation of hernia sac were randomly divided into 3 groups: high-pressure group (12 mm Hg, HP group, n = 26); low-pressure group (8 mm Hg, LP group, n = 20); open operation group (OP group, n = 22). Heart rate (HR), blood pressure, and end-tidal CO 2 (PetCO 2 ) were recorded, as well as the levels of adrenocorticotropic hormone (ACTH) and cortisol (COR) were measured by ELISAs before operation, during operation, and after operation, respectively.Results: After establishing capnoperitoneum, HR, blood pressure, and PetCO 2 were significantly increased in the HP group compared with the OP and LP groups (P < 0.05). Comparing the intraoperatively measured ACTH and COR concentrations of the HP group to the LP group, we noted higher values in the first (P < 0.05). There was no significant difference in the postoperative concentrations of ACTH and COR among the HP, LP, and OP groups. Abbreviations: ACTH = adrenocorticotropic hormone, ASA = American Society of Anesthesiologists, COR = cortisol, DBP = diastolic blood pressure, ELISA = enzyme-linked immuno sorbent assay, HP = high-pressure, HR = heart rate, LP = low-pressure, OP = open operation, PetCO 2 = end-tidal CO 2 , SBP = systolic blood pressure, SD = standard deviation.