An 86-year-old man, with a medical history of coronary artery bypass grafting with the right gastroepiploic artery 20 years prior, was admitted to our hospital for right-sided heart failure. Computed tomography findings revealed an intrapericardial diaphragmatic hernia of the transverse colon compressing the right ventricle. The hernia was successfully repaired, and the patient recovered without any complications. Diaphragmatic hernia is rare but may be a lethal complication following coronary artery bypass grafting. We should be aware of the possibility of this condition.