ObjectiveTo summarize the clinical manifestations and surgical treatment of unroofed coronary sinus syndrome（UCSS）. MethodsNine patients underwent surgical repair for UCSS from Jan. 1999 to Jun. 2009 in our hospital, and the patients included 3 with typeⅠa, 1 with typeⅠb, 1 with typeⅡa, 3 with type Ⅲa, and 1 with type Ⅲb UCSS. The diagnosis of UCSS was made by echocardiography in 6 patients and by the surgical exploration in 3 patients. Persistent left superior vena cava（PLSVC）was found in 7 cases; 3 cases with PLSVC directly draining into the left atrium(Ⅰa) were reconstructed by the intra-atrial routes to guide PLSVC to the right atrium, and 4 cases with PLSVC draining into the coronary sinus and coronary sinus orifice opening to the left atrium and right atrium (1 case,Ⅱa) and left atrium (3 cases,Ⅲa) were dealt with the abnormal coronary sinus orifice. Other associated cardiac lesions were corrected concomitantly. ResultsTwo cases had early complications and the other 7 cases had smooth recovery after operation; all the patients were cured and discharged. Eight cases were followed up for 2 months to 5 years and there was no death or late complications.ConclusionUCSS is a rare congenital cardiac anomaly and is difficult to diagnose preoperatively; so careful exploration should be done during operation. Different surgical approaches should be chosen according to the types of communication between PLSVC and cardiac atrium, the positions of abnormal sinus ostium, and other cardiac lesions. Satisfactory prognosis can be obtained if physiological correction is achieved.