We report a 40-month-old black male with nephrotic syndrome who developed chylothorax associated with superior vena cava (SVC) thrombosis. To our knowledge, this is the third reported case of spontaneous SVC thrombosis in a nephrotic patient and the first in which chylothorax was also present. Ultrasonography of the pleura and thoracic vasculature was invaluable in making the diagnosis and monitoring the resolution of this condition during treatment. Contrary to previous reports, thoracic chylous effusions complicating uncontrolled nephrotic syndrome do not originate exclusively as a consequence of abdominal pathology, but rather as this case demonstrates, they can occur from lymphatic obstruction caused by thoracic vein thrombosis.