Since 1975, only approximately 60 saphenous vein graft aneurysms have been reported in the medical literature. We now report this unusual finding in a male cadaver who had undergone a recent coronary artery bypass grafting procedure. Although aneurysm formation is an unusual complication of saphenous vein graft surgery, the diagnosis must be suspected particularly in the face of a mediastinal mass on chest radiography in patients who have undergone coronary artery bypass grafting. Needle biopsy in these cases may prove lethal. We believe this to be the first description of this complication in a cadaver.