The primary objective of the study was to identify the incidence of catheter tip malposition as determined by postoperative radiography after central venous cannulation by right and left internal jugular venous routes in pediatric cardiac surgical patients. The secondary objective was to determine the relative risk of malposition between the 2 approaches into specific major thoracic veins other than the right superior vena cava. A prospective observational study. A tertiary cardiac care center. Pediatric patients undergoing cardiac surgery INTERVENTIONS: Internal jugular vein cannulation with ultrasound guidance. Two hundred pediatric patients undergoing cardiac surgeries for cardiac anomalies with Risk Adjustment in Congenital Heart Surgery scores of 1- to-6 were included in the study. After anesthetic induction, 50% of the patients were cannulated via the right internal jugular vein (RIJV group, n = 100), and the other 50% via the left internal jugular vein (LIJV group, n = 100). The position of the catheter tip was ascertained by a plain chest x-ray. The central venous catheter tip was deemed to be malpositioned if the tip was in the ipsilateral or contralateral subclavian vein or in the contralateral internal jugular vein. In the RIJV group, 4% of the patients had the central venous catheter tip in a malposition (4/100). In the LIJV group, 6 of the 100 patients had a left superior vena cava and were excluded. In the rest of the LIJV group, the central venous catheter tip was in a malposition in 22.3% of patients (21/94, relative risk: 6.90, p < 0.001). Malposition into the right subclavian vein was more frequent with the left internal jugular vein access (11/94, 11.7%) compared with the right internal jugular vein access (relative risk: 13.12, p = 0.015). The incidence of a malposition of a central venous catheter tip after either right or left internal jugular vein approach was ascertained. The relative risk of a malposition occurring with the left internal jugular approach was higher, and the most common site of malposition was in the right subclavian vein.