One of the main problems encountered during the Mustard's procedure for transposition of the great arteries is sizing of the baffle especially in small infants. While a small baffle results in caval obtruction, a large buffle swelling in to the common atrium obstructs pulmonary venous outflow. While performing the Mustard's procedure on a 2 month old infant weighing 4 kg we had a similar problem. The baffle needed for adequate venous drainage was encroaching on the pulmonary vein orifices due to the small size of the atrium in the infant. We solved the problem by elongating the right atrial incision through the right pulmonary veins which were single in this case and enlarging the pulmonary venous atrium by placing a triangular atrial patch. The wide portion of the patch was sutured to the bottom end of the incision in the pulmonary veins and it narrowed towards the right atrium. While this type of enlargement has been reported through the posterior of the left atrium especially for reoperations, we have enlarged the left atrium through the single right pulmonary vein. We believe this type of atrial exterior patching too can solve problems associated with bulging baffles especially in small infants.