The controversy over the need to explore the asymptomatic contralateral groin for the existence of a hernia sac in children who undergo inguinal hernia repair is not easy to resolve. To detect the patency of the contralateral processus vaginalis, we used intraoperative nonpuncture laparoscopy. By insufflating carbon dioxide and inserting a laparoscope through the open hernia sac, the opening of the contralateral processus vaginalis was clearly seen. A patent processus vaginalis on the opposite side is considered to be a potential hernia. A total of 74 children, 56 boys and 18 girls, were involved in the study. All of them had inguinal dissection on the symptomatic side and laparoscopy was performed through the opened hernial sac. A contralateral patent processus vaginalis was found in 22 children, 14 boys and 8 girls, by laparoscopy. The results were confirmed by surgical exploration of the opposite groin. There were no false-positive and no false-negative results. Intraoperative non-puncture laparoscopy is a simple, safe, and accurate method of detecting patency of a contralateral processus vaginalis. When used instead of routine bilateral exploration, this procedure can avoid many unnecessary surgical operations.