<p>Duplication of superior vena cava (SVC) is a rare anomaly. The incidence of double SVC in general population is 0.3% whereas in patients with congenital heartdisease it varies between 10-11%. Double SVC caseshave clinical importance if especially the one on the leftside drains into the left atrium. Moreover, double SVC issurgically important in the presence of congenital heartdisease. In this article, we presented adult patients whoincidentally diagnosed with double SVC, one drainedinto the right atrium while the other into the left atriumand discussed the embryologic basis of these patent vessels<br></p>