In 38 boys with clinical unilateral inguinal hernias (CUIH), the contralateral processus vaginalis was examined laparoscopically before surgical manipulation at the time of elective inguinal herniorrhaphy. General anesthesia was used in each case, and a 30°, 2.7-mm laparoscopic was introduced using standard techniques. Positive laparoscope findings prompted surgical exploration. The age range was 2 to 134 months. Twenty-four had a right CUIH, and 14 had a left CUIH. Overall, the contralateral processus vaginalis was patent in 52.6%, with 58.3% and 42.8% patency on the nonclinical left and right sides, respectively. In boys under 2 years of age, 50% of those with a right CUIH had a contralateral patent processus vaginalis, as did 60% of those with a left CUIH. In two of these 38 patients in whom there was no clinically proven hernia, the only patent processus vaginalis was on the side opposite the one with a clinical history. Laparoscopic examination of the internal inguinal ring provided accurate information useful in determining the need for contralateral inguinal exploration in these 38 children. © 1994.