Prevalence of primary coronary cameral fistula (CCF) is extremely rare, especially for CCF with the drainage site into the left ventricle. We describe a 45-year-old patient with chest tightness in whom a giant aneurysm associated with proximal right coronary artery (RCA), and the distal end of RCA terminated into the left ventricle through a fistula was discovered by echocardiography. Dual-source computer tomography revealed the CCF-related giant RCA aneurysm. The drainage site and coexistent abnormality could not be visualized well by coronary artery angiography because of the severely diluted contrast medium into the aneurysm. Finally, the patient received surgical treatment and is asymptomatic now.