Congenital fistula between the first diagonal branch of the coronary artery and left ventricle with a giant coronary artery aneurysm is extremely rare. We present the case of a 50-year-old asymptomatic male patient with such a condition that was diagnosed by transthoracic echocardiography, coronary computed tomography angiography, and coronary angiography. The patient was treated by surgical fistula closure under cardiopulmonary bypass. The postoperative coronary computed tomography angiography showed the patient got a complete cure, and the patient remains asymptomatic after 5-year follow up.