We present a rare case of unroofed coronary sinus in a patient who underwent supra-annular tricuspid valve replacement with consequent drainage of the coronary sinus to the right ventricle. It is unclear whether the coronary sinus was unroofed congenitally or iatrogenically. This rare setup resulted in significant cyanosis. The abnormal drainage was successfully closed via trans-catheter delivery of covered stents with resolution of the cyanosis. © 2017 Wiley Periodicals, Inc.