Background: Unroofed coronary sinus (UCS) is a rare subtype of atrial septal defect. It is frequently associated with a persistent left superior vena cava and is often part of a more intricate cardiac malformation.
Case Summary: This report describes a rare case of an adolescent patient with UCS featuring atrial situs solitus, absence of the right superior vena cava and a persistent left superior vena cava draining into the left atrium consistent with total unroofing of the coronary sinus.