Obstruction of venous return in the mediastinum or thoracic inlet is well recognized, particularly in oncological practice. In most cases the obstruction is of the superior vena cava. For such venous obstruction to occur following treatment for lung cancer usually implies malignant lymph node involvement and therefore a grave prognosis. This report describes a patient who developed unilateral signs of impaired venous return from the head, upper trunk and upper limb following treatment for lung cancer. The cause was found to be compression of the left brachiocephalic vein by normal anatomical structures as a result of mediastinal shift following pulmonary lobectomy and radiotherapy. This case, together with others reported in the medical literature, suggests that the development of isolated brachiocephalic vein obstruction does not necessarily have the same ominous implications as the development of superior vena caval obstruction.