The muscular, collagen and elastic fiber dispositions of the superior mesenteric vein wall were studied in 40 antaomic specimens by various mesoscopic and microscopic techniques. The muscular fibers follow a crossed spiral pattern. Close to the superior mesenteric vein junction with the portal vein, these spirals are elongated and they become progressively flattened towards the ileocecal region where they tend to a circular disposition. At the tributary vein entrance, circular bundles of the intima layer of the superior mesenteric vein bend towards its ostium thus forming annular thickenings. The collagen fibers form pantographic networks in the superior mesenteric vein wall, crossing each other at different angles in the three layers of the vessel. The elastic fibers follow the same disposition as the muscular fibers. Morphofunctional considerations are discussed.