The contralateral internal ring of 96 children was examined laparoscopically during unilateral hernia repair to minimize the chance of development of contralateral hernia. Laparoscopy was performed through the hernia sac before ligation. Of 29 patients with positive laparoscopic findings, 28 had a patient processus vaginalis as confirmed by simultaneous contralateral exploration and there was one false positive. Patency of the contralateral processus vaginalis was found in 28 (29 per cent) of the 96 patients. Children under 2 years of age had a significantly higher incidence of patent contralateral processus vaginalis than older patients. The only complication of the procedure was wound infection in two patients. This is a simple, safe and accurate procedure to select children for contralateral surgical exploration.