Although either coronary artery aneurysm or coronary arterio-venous fistula may be found infrequently during coronary angiography, it is very rare to see combination of both structures. Here we present a case of coronary artery fistula combined with a large aneurysm. The aneurysm resembled a mass just beside the left heart border in the chest X-ray (CXR) film. The patient came to our hospital for chest pain. A grade 2/6 continuous murmur was noted over left upper sternal border. The mass was proved to be a coronary artery aneurysm at last by coronary angiogram after many examinations. Two coronary aterio-venous fistulae were also noted. This reminded us that coronary artery aneurysm could be one of the differential diagnoses of paracardiac mass during the interpretation of a CXR film. A high level of suspicion and a detailed physical examination combined with an adequate image studies, (such as echocardiography, computed tomography, magnetic resonance image, or coronary angiography) may provide accurate diagnosis and avoid painful, invasive examinations.