Five of 139 patients with persistent common atrioventricular canal (AVC) confirmed at necropsy had lived to the age of 46 yr or older. The complete type of the malformation was present in one, the transitional type in one and the partial type in three. The oldest of the latter group was 79 yr of age at the time of death. In a study of ages at death among 139 cases of AVC the following observations were made. Of the 91 patients with the complete type of AVC, 37% survived more than one year and 17.6% more than five years. Of the 48 patients with the transitional and partial types of the defect 67% lived more than one year and 37.5% beyond 5 yr. One of the cases was highly unusual in that AVC was associated with corrected transposition.