About seventy cases of congenital heart block have been recorded. Yater's1review of cases prior to 1929 included only thirty cases of well established block. The criteria used by him and in subsequent reviews were auriculoventricular dissociation proved by a graphic method in a relatively young person, development of bradycardia at a fairly early age, and absence of a history of infection which might cause heart block. In 1934 Hays2collected twelve additional cases. Since then about twenty-six additional cases have been reported. The age at which the diagnosis of heart block has been made varies from birth up to 20 years. Only five cases including our case have been diagnosed before birth. Yater,1Witt,3Heubner4and Ottow5have made a prenatal diagnosis of complete heartblock. The diagnosis of heart block before birth has also been made by White, Eustis and Kerr,6