BACKGROUND: Incorrect positioning of central venous catheter leads to serious complications. To prevent these complications, catheter tip should be at the superior vena cava and right atrial junction. METHODS: We studied 60 right internal jugular catheterizations in infants and children undergoing surgery for congenital heart disease. To confirm the optimal depth of central venous catheter, we measured the distance from the skin puncture site to subclavian vein-right atrial junction using transesophageal echocardiography. RESULTS: The measured distance highly correlated with the patient height. Based on these data, following guideline could avoid intra-atrial placement in 94% of the time: optimal depth of insertion (cm) = 2.5 + (0.06 x height). CONCLUSIONS: We postulate that initial using a simple practical guideline could prevent malposition of central venous catheter.