Fourteen cases of malposition of a permanent central vein catheter for hemodialysis or poor blood flow associated with thrombosed central veins but correct catheter positioning, in 13 patients suffering from end stage renal disease, presented from September 1991 to December 2003 among 385 permanent central vein catheters for hemodialysis (3.6%). There were 8 episodes of catheter tip malplacement in the azygos vein (1 case), hemiazygos vein (1), left internal thoracic (mammalian) vein (1), contralateral innominate vein (5) and 6 cases with correct anatomical catheter tip placement but with blood inflow from the catheter through the collateral vein system because of thrombosis of a major vein trunk (hemiazygos vein system (2), azygos vein (2), ascending lumbar veins (1), or portal vein system (1)). The malposition was diagnosed using roentgenography, with or without contrast, and computer tomography. In 3 cases the catheter was removed, in 5 cases the position was corrected. In the remaining 6 cases its function was maintained using anticoagulation or/and thrombolytic therapy. In conclusion, the placement of a permanent central vein catheter for hemodialysis must be followed by simple or contrast medium x-ray evaluation of its correct position or function. The malposition must be corrected whereas in the case where there is no alternative solution the function of the catheter may be maintained in the incorrect position using a combination of anticoagulation or/and thrombolytic therapy.