Coronary artery aneurysm (CAA) is defined as dilatation of the coronary artery that is more than 1.5 times the diameter of normal adjacent segments. A coronary artery with a diameter more than 2 cm is termed as 'giant aneurysm' and only a few cases have been described in the literature. In adults, CAA is predominantly atherosclerotic in origin; however, other causes include Kawasaki disease, autoimmune disease, trauma, infection, dissection, congenital malformation and angioplasty. Clinical presentation, prognosis and management of a giant CAA are not well defined due to limited experience. We present the case of a patient with giant aneurysm of the proximal segment of the right coronary artery.