Laparoscopic surgical procedures, employed even in the paediatric age, bearing both diagnostic and therapeutic value, are currently used in the evaluation of peritoneal-vaginal duct patency during surgery for controlateral inguinal hernia or other diseases requiring opening of abdominal wall.From January 1996 to December 2000, at the Department of Pediatric Surgery of the University of Siena a prospective study protocol has been performed to evaluate the effectiveness of laparoscopy versus traditional surgery in showing patency of peritoneal-vaginal duct.From our study we have been able to see how this laparoscopic procedure is well tolerated by children and parents, and is lacking in clinical complications. Patency of peritoneal-vaginal duct has been pointed out in 21.73\% of cases. This result is in line with the international literature; in fact, the majority of authors have found a negative controlateral exploration in 50-80\% of patients examined, thus confirming the uselessness of routine surgical controlateral inguinal exploration in hernia cases.The use of diagnostic laparoscopy in the study of peritoneal duct patency is a rapid and relatively easy technique, practically without intra- and peri operative risks. It allows an easy solution of the diagnostic doubt, without the need to necessarily perform a traditional explorative surgical procedure