An 81-year-old woman presenting with severe congestive heart failure was found to have a congenital right coronary fistula draining into the superior vena cava. The diagnosis was suspected on transthoracic two-dimensional echo-Doppler study and confirmed with coronary angiography. Transesophageal echocardiography and magnetic resonance imaging were nondiagnostic. An attempt to close the fistula with transcatheter embolization using a detachable latex balloon was unsuccessful because of the very large size of the fistula. Follow-up showed a favorable outcome with medical therapy. Despite the advent of more recent diagnostic and therapeutic techniques, management of such large fistulae remains unresolved.