Coronary artery aneurysm (CAA) is an uncommon disease observed in only 0.15-4.9% of patients undergoing coronary angiography. CAA are defined as dilated coronary artery sections exceeding by 1.5 times the diameter of normal adjacent segments or of the patient's largest coronary vessel. Occasionally, CAA enlarge enough to be called giant CAA. We report the case of a 78-year-old man, with known chronic ischemic cardiomyopathy and a history of prior coronary artery bypass surgery (with a left internal mammary artery graft to the left anterior descending coronary artery and saphenous venous graft to the obtuse marginal branch), who was referred to our cardiology department for progressive dyspnea. Echocardiography showed severe mitral regurgitation suggesting replacement; coronary angiography revealed three-vessel coronary artery disease, left internal mammary artery patency, saphenous vein graft occlusion and an aneurysm of the mid right coronary artery. Cardiac magnetic resonance confirmed this finding, showing a giant CAA (65 x 75 mm) with a large endoluminal thrombus. Treatment is not standardized and may include medical therapy, percutaneous treatment and surgical intervention; our patient underwent percutaneous coil embolization. One-month angiographic follow-up showed successful obliteration. The patient underwent surgical mitral valve replacement without any complications. At 9-month clinical follow-up, he was asymptomatic; transthoracic echocardiography showed an ejection fraction of 44% without prosthetic mitral regurgitation.