In coronary artery bypass grafting, we prefer the right gastroepiploic artery as an adjunct to the internal mammary arteries, due to its comparable size to the mammary artery, flow, length, freedom of atherosclerosis, pharmacologic responses, and patency rate. No major gastric complications after the use of the gastroepiploic artery have been reported yet. We report gastric perforation due to excessive coagulation of side branches of the gastroepiploic artery supplying the greater curvature of the stomach.