The diagnosis of inguinal hernia is usually a simple matter even in a small infant. The parents' history of a bulge in the groin on straining, observation of such a mass, and palpation of the distended sac make the diagnosis relatively easy. The detection of an empty sac or patent processus vaginalis on the opposite side requires more experience and diagnostic acumen. It was this problem of the contralateral side which led to the review of 1,000 cases from the surgical service of the Children's Hospital, Louisville. Material and Procedure This series covers a 5-year period and includes staff patients operated upon by house officers under our supervision, and the private patients of both of us. These were all consecutive patients with hernia, except that those with undescended testicle were excluded. The Figure shows the distribution of the patients by age. The policy of the service has been to advise