Axillosubclavian vein thrombosis produced by retrosternal thyroid. Several causes of axillosubclavian vein thrombosis have been described. Trauma to the subclavian vein by pacemaker wires or central venous lines as well as the so-called effort thrombosis have been recognized as frequently diagnosed precipitating factors. A patient is herein presented with thrombosis of the subclavian vein caused by a giant substernal thyroid compressing the innominate vein. 