A 73-year-old man presented with multiple giant coronary artery aneurysms. Twelve years prior to the presentation, he had undergone coronary artery bypass grafting. At that time, he exhibited small aneurysms (16 mm diameter) in the right coronary artery and a single aneurysm (10 mm diameter) in the left circumflex artery. During follow-up, the aneurysms gradually increased in size (to 45 and 30 mm, respectively, at 12 years after surgery). We resected all of the aneurysms and performed coronary artery bypass grafting of the left circumflex artery through re-sternotomy.