Management of the contralateral inguinal region in children with a unilateral inguinal hernia remains controversial. The role of laparoscopy in evaluation for contralateral patent processus vaginalis remains unclear. We report the results of an investigation of 1676 consecutive children younger than 10 years of age who underwent unilateral inguinal hernia repair between May 1992 and January 2003.Bilateral inguinal hernias were noted preoperatively in 194 of the total of 1870 patients, leaving 1676 patients in the study group. In all patients, the contralateral inguinal region was examined under general anesthesia and the operating surgeon noted whether or not a contralateral patent processus vaginalis was suspected. All patients then underwent attempted laparoscopic evaluation of the contralateral inguinal region at the time of unilateral inguinal hernia repair.Laparoscopy was successful in 1603 cases (95.6%) but 73 patients (4.4%) had hernia sacs that were too thin to allow insertion of a 3-mm cannula and 2.7-mm 70-degree telescope. A contralateral patent processus vaginalis was identified in 643 of the laparoscopically examined children (40.1%). At the examination, it was predicted that 446 of the 1603 patients would have a contralateral patent processus vaginalis. Laparoscopy confirmed the presence of a contralateral patent processus vaginalis in 192 (43.0%) of the children predicted to have a contralateral patent processus vaginalis. A contralateral patent processus vaginalis was not suspected from the examination under anesthesia in 1157 of the examined children, and the absence of a contralateral patent processus vaginalis was confirmed by laparoscopy in 706 of these children (61.0%); however, a contralateral patent processus vaginalis was found in 451 (39.0%) of this group.We conclude that examination under anesthesia is a poor predictor for the presence or absence of a contralateral patent processus vaginalis. Laparoscopy can reliably evaluate the contralateral inguinal region and is the best method to evaluate for the presence of a contralateral patent processus vaginalis.