Ninety-four infants with unilateral indirect inguinal hernia underwent repair and diagnostic pneumoperitoneum (DPP). Contralateral groin exploration was performed in all patients including those with a negative DPP result. Thirty-seven (39%) of the 94 patients had a positive DPP result, and 36 of 37 (97%) had a patent processus vaginalis (PPV) on the side contralateral to the clinical hernia. Fifty-seven (61%) of the 94 patients had a negative DPP result, and 54 (95%) of these had no PPV. Female patients had a 1:1 correlation between DPP and PPV. DPP can predict the presence of PPV in the contralateral groin of patients with unilateral hernia with precision and minimizes the need for diagnostic groin exploration.