Unroofed coronary sinus syndrome is an uncommon anomaly which is caused by incomplete formation of the left atriovenous fold and it is usually associated with persistent left superior vena cava. It may be diagnosed by cardiac catheterization and cineangiography but, if it is not diagnosed, it can bring out significant complications due to right to left shunt, such as brain abscess, cerebral embolism, transient ischemic attack, arterial desaturation and there will reduced patient`s life expectancy. Therefore corrective operation was needed. A case of unroofed coronary sinus syndrome which combines with valvular heart disease was experienced at the department of thoracic & cardiovascular surgery of Kosin medical college. The patient was 49 years old female and she complained dyspnea on exertion for 2 yrs. Cardiac catheterization with cineangiography and both superior venacavogram were performed for diagnosis and she was diagnosed as unroofed coronary sinus syndrome combined with mitral and tricuspid regurgitation. Surgical correction was accomplished by reroofing of coronary sinus with pericardial patch, closure of atrial septal defect and annuloplasty of both atrioventricular valves. Postoperative results were satisfactory and course of recovery was uneventful. We report a case of unroofed coronary sinus syndrome with review.