Aneurysm of a saphenous vein graft after coronary artery bypass requires surgical resection because of its potential for rupture. This report describes a case of aneurysm formation in a 55-year-old man who underwent coronary artery bypass operation in 1977 and orthotopic heart transplantation 7 years later. A proximal vein graft remnant that had been ligated at the time of transplantation developed into a 5-cm aneurysm. In patients who have undergone previous coronary artery bypass operation, we recommend that the entire vein graft stump be excised and oversewn at the aortosaphenous anastomosis at the time of transplantation.