Central venous catheterization (CVC) is a common procedure but catheter misplacement is a frequent complication and can be lethal. Most CVCs are inserted at a recommended mean depth of 15 cm from the skin puncture site. Chest radiographs are used to confirm the positioning of CVCs, with the carina regarded as a reliable landmark for tip placement. The C-length, defined as the distance from the edge of the right transverse process of the first thoracic spine to the carina, can be measured on posteroanterior chest radiographs. To test the accuracy of C-length based CVC placement, 637 adult patients scheduled to undergo elective major abdominal procedures and neurological surgical procedures requiring CVC were randomized to undergo either the 15-cm guided method or the C-length guided method for placement of the CVC tip into the superior vena cava (SVC). All the CVC tips in the C-length group were successfully placed in the SVC. These findings indicate that the pre-measured C-length using two landmarks can be used to determine the insertion length and to place the CVC tip successfully into the SVC.