Two cases of double superior vena cava were found among 300 Japanese cadavers dissected at Kyoto University from 1980 to 1989. Case 1 was an 82-year-old male patient who died of cerebral infarction. Case 2 was a 39-year-old well-developed male patient who died of sepsis. They had no history of cardiovascular disorders. Common features in both cases are as follows: In addition to a right superior vena cava with normal appearance located in the normal position, on the left side, a normal-looking extra superior vena cava persisted and descended vertically in front of the aortic arch between the left pulmonary vein and the left auricle, traversed the coronary sulcus and finally drained into the right atrium. No differences in diameter were found between right and left venae cavae. No communicating vessels were present between them. Therefore, both cases, which had a persistent left superior vena cava draining into the coronary sinus, may be classified as McCotter's 1st type (1916) or Donadio's 3rd type (1925). Furthermore, in Case 2, the double azygos vein persisted symmetrically, suggesting the 4th type of Nandy and Blair (1965). In addition to venous anomalies, Case 2 had arterial anomalies such as the right subclavian artery arising as the last branch of the aortic arch similar to the G type of Adachi (1928), and the right vertebral artery arising from the right common carotid artery. The present cases are considered to be the 53rd and 54th cases of double superior vena cava found in Japanese cadavers, and the 18th and 19th cases of double superior vena cava without communicating vessels between them.