A 59 year-old male diagnosed as unstable angina underwent off-pump coronary artery bypass surgery using in situ left internal mammary and right gastroepiploic artery grafts. During harvesting the right gastroepiploic artery, there was no abnormal finding in intraabdominal organs including stomach and liver. He was discharged at the 3rd postoperative day without complication. In case of using in situ right gastroepiploic artery, we recommend gastrofberscopic study at regular follow-up, The patient underwent the gastrofiberscopic study at postoperative 3rd month and diagnosed as advanced gastric cancer on the posterior wall of gastric fundus. At 5th postoperative month, total gastrectomy without intraoperative injury of the right gastroepiploic artery was performed at the department of general surgery. He was discharged at the 9th postoperative day. Follow-up coronary angiography performed at the 1st postoperative year demonstrated patent grafts including right gastroepiploic artery.