There is no established operative procedure for the correction of transposition of the great vessels, one of the largest causes of infant mortality in congenital heart disease. Some improvement has been reported with the surgical approaches described by Blalock and Hanlon,3 Baffes,2 and Senning.6 A one-stage intracardiac procedure has been devised which would accomplish total venous transposition under what would seem to be an acceptable operative risk. Similar procedures have been described by Albert,1 Merendino et al.,5 and Creech and co-workers.4 To test the success of the procedure to be described would require dog preparations of congenital transposition not available to us, and since successful completion of the venous preparations in a dog results in total separation of the two major circulations, no survivals could be expected and in effect confirm the success of the transposition. Method A series of dogs was prepared for