Superior vena cava (SVC) syndrome rarely responds to conservative treatment. We report the case of a 2-month-old boy with SVC syndrome and bilateral chylothorax after surgical repair of the hemitruncus. Medical management with low-dose heparin, dipyridamole, and aspirin resulted in improvements of head swelling and chylothorax. The chyle had disappeared 46 days postoperatively. Compensatory growth of collateral vessels was also found. Although surgical repair is sometimes advocated in patients with SVC syndrome, medical treatment is an important alternative if the risk of surgery is too high.