Combined resection of the superior vena cava is sometimes challenging during radical surgery for malignant mediastinal tumors. We report a case of a 21-year-old man with a malignant mediastinal germ cell tumor who underwent surgical resection with superior vena cava reconstruction involving an extrathoracic temporary bypass from the right brachiocephalic vein to the right atrium using a venous return cannula because of left brachiocephalic vein occlusion. This is a convenient and safe optional technique providing an excellent intrathoracic surgical view for temporary superior vena cava bypass in patients with invasive malignant mediastinal tumor associated with venous return through the hemilateral brachiocephalic vein.