Coronary sinus Ostial atresia（CSOA） is a rare cardiac malformation. The morbidity rate is 0.1%(1). We report here on a rare case of an incidentally found CSOA with unroofed coronary sinus(UCS) and persistent left superior vena cava(PLSVC) in an adult patient. Diagnostic methods included echocardiography, multidetector row computed tomography.