Two uncommon cases of vein obstruction are presented. In the first case a syndrome of superior, caval vein obstruction was caused by idiopathic fibrous mediastinitis involving the vein wall, and creating a tumefaction in the lumen of the vein simulating the existence of a benign tumor (fibroma) of the wall. This tumefaction was removed by endvenectomy, and the venotomy was repaired by a pericardial patch. In the second case the obstruction of the right subclavian vein was caused by a stenosed valve without signs of inflammation nor consecutive thrombosis. Until the present day no other similar case of a stenosed valve in the right subclavian vein has been reported.