Varicose veins are not generally used as arterial bypass grafts despite their physiological endothelial flow surface. The large, irregular diameter and the thin wall renders these veins inadequate. Experimental studies have shown that a considerable reduction in the diameter of veins can be achieved by external wrapping without the generation of obstructing folds of the vein wall. A Dacron mesh tube surrounding varicose veins was used as a bypass graft in 13 infrainguinal arterial reconstructions. Ligated larger side branches and connections of the mesh segments caused irregularities of the otherwise smooth flow surfaces. Ten grafts were patent after a mean follow-up of 17 months. Two grafts have remained patent despite severe outflow obstruction in one and proximal occlusion in the other; both underwent successful interventions. The antithrombogenic properties of these grafts were partly due to a marked increase of the vasa vasorum. Externally constricted varicose veins may be used as arterial bypass conduits with good intermediate-term patency.