Abstract A giant coronary aneurysm is rare entity and it is defined if the diameter is 4–fold greater the reference vessel diameter or if it is > 20 mm in diameter. We report the case of a 73–years–old man without prior history of cardiac disease, admitted in Emergency Department for abdominal pain with normal ECG. Abdominal CT scan showed no pathological findings. At thoracic level it was reported a suspected pericardial cyst (75x80 mm), with partial compression of right chambers (Fig. 1). Echocardiography confirmed the presence of a giant round cystic–appearance lesion characterized by the presence of an anechoic space with internal echogenic swirling flow pattern at the level of right atrioventricular groove with mild compressive effect on right chambers. (Fig. 2). The color Doppler mode showed a faint signal, without a clear evidence of flow origin. A bubble test with agitated saline contrast medium injected through antecubital vein, shows no evidence of contrast uptake by the mass. In order to better characterize the lesion, we use echocardiographic contrast agent (SonoVue®), which showed a clear pattern of blood flow inside the mass with a probable origin at a very limited region (Fig. 2a–2b). At that level it was also possible to sample an ECG–synchronized systo–diastolic pulse–wave (PW)–Doppler pattern (peak velocity 125 cm/s), typical for a coronary artery flow. According to these echocardiographic findings, we supposed a giant right coronary aneurysm. Coronary Computed Tomography Angiography with 3D reconstruction showed a giant aneurysm of the right coronary artery at mid–level, preceded by a mild aneurysm of the proximal tract and two small aneurysms of the circumflex artery and diffuse atherosclerosis diseases with significant stenosis on mid left anterior descending artery (LAD). The coronary angiography confirmed the presence of the giant aneurysm in mild tract of right coronary artery preceded by a small one in the proximal tract andthe two small aneurysm of the circumflex artery and a critical stenosis of mid tract of LAD. The patient underwent surgical treatment of the aneurysm and coronary artery bypass graft (Fig. 3). Computed Tomography Coronary Angiography is the best method for coronary artery anatomy and coronary abnormalities. In case of giant coronary abnormalities, the use of echo contrast agent provides further important information about perfusion and/or flow assessment and it helped to clarify the diagnosis.