In patients with superior vena cava syndrome, the form of the collateral circulatory system whichcommuni-cates with the inferior vena cava via various systemic veins usually varics. We found an instance ofunusual collateral circulation : direct communication between the systemic and pulmonary vein in a woman withsuperior vena cava syndrome caused by metastatic lymph node enlargement. In this report, we describe the CT andradionuclide venographic findings.