The successful operations upon abnormalities of the outflow tracts of the heart suggest that surgical measures may also be applied to the correction of abnormal inflow tracts. Technically the anastomosis of veins to the auricle has been proved feasible in the experimental animal. Therefore, it should be possible to correct abnormally placed pulmonary veins in man. A wide variety of such anomalies occur. In 55 of 136 reported cases, all the oxygenated blood from the lungs was returned to the right heart through anomalous vessels. Thirty-five per cent of these cases of complete diversion were accompanied by other major cardiac defects. It is estimated that 50% or more of the return flow from the lungs must reach the right heart to produce clinical symptoms. Two cases are presented of persistence of the left superior vena cava which transmitted all the freshly oxygenated blood to the right auricle, by way of the left innominate and the right superior vena cava. The clinical picture was that of growth retardation, minimal cyanosis, a huge hyperactive heart, a loud left mesocardial systolic murmur, pulsating shadows in both upper pulmonary fields, and nearly identical oxygen-saturation of blood obtained from the right heart and femoral artery. One case is reported in which all the oxygenated blood from the lungs is carried to the right auricle by way of the ductus venosus. Surgical correction of the abnormality of these cases by transplantation of one or more of the veins would have been possible. However, no case known to the authors has yet been successfully corrected.