The circulatory anatomy of the arterialized cephalic venous flap was investigated radiographically in five fresh cadavers. Microfil, which was dripped from the caudal end of the cephalic vein, flowed first into the concomitant veins and then into an intimate vascular network around the cephalic vein. The Microfil then flowed to a septocutaneous perforator of the radial artery through the vascular network around the cephalic vein. This suggests that in the arterialized cephalic venous flap there is a circulatory pathway by means of the cephalic vein to the venous network around the cephalic vein, to the arterial network around the cephalic vein, to the arterial system, and to the venous system returning to the cephalic vein.