This report describes a patient with a rupture of the noncoronary sinus of Valsalva caused by erosion of its wall by a large right atrial vegetation not attached to the tricuspid valve without aortic valve involvement. The rupture site was located right posterior to the tricuspid septal leaflet and communicated both with the right atrium and the right ventricular inflow tract, resulting in a significant left-to-right shunt leading to severe right heart failure and shock. The diagnosis was made by transthoracic and transesophageal echocardiography. To our knowledge no similar case has been reported in the literature.