Background: Unroofed coronary sinus syndrome (URCSS) is a spectrum of cardiac anomalies in which part (partial type) or the entire common wall (complete type) between the coronary sinus (CS) and left atrium is absent. It is commonly associated with a persistent left superior vena cava (PLSVC). The PLSVC can even anomalously connect to the left atrium in complete type anomaly. URCSS has been reported to be associated with delayed diagnosis and life-threatening cerebral injury. The purpose of the present study was to review our experience with surgical correction of this often-concealed malformation and discuss methods for reducing diagnostic omission. Methods: Thirty-six patients with URCSS who underwent surgical treatment from 1998 to 2015 in our institution were enrolled in this retrospective analysis. Results: The mean age of the patients was 21.8 ± 20.9 years. Type I anomalies were found in 15 (41.7%) patients, type II in 4 (11.1%), type III in 6 (16.7%), and type IV in 11 (30.6%). A patient presenting with URCSS without other defects was identified in six (16.7%). One patient (2.8%) had a history of paradoxical embolisation. Twenty-five patients (69.4%) were diagnosed before surgery. Ten patients (27.8%) were diagnosed with URCSS intraoperatively. One patient (2.8%) was diagnosed with URCSS by follow-up echocardiography after device occlusion for atrial septal defect. Coronary sinus ostium dilation was the most important clue leading to partial type lesion disclosure intraoperatively. The anomalous PLSVC of 15 patients was repaired using roof tunnel technique in four (26.7%) cases, baffle redirection in eight (53.3%) cases, posterior left atrial wall plicating in two (13.3%) cases, and extracardiac bypass in one (6.7%) case. Postoperative complete atrioventricular block occurred in one patient (2.8%). One patient died postoperatively (2.8%). All patients are doing well after discharge from hospital. Conclusions: Diagnostic suspicion can contribute to lesion disclosure. Surgical correction has good long-term outcomes and low risks. © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ)