In pediatric patients, central venous catheterization (CVC) is necessary for administration of fluids, drugs, high concentration electrolytes, vasopressors or inotropic drugs, transfusion, intravenous nutrition, and dialysis. Using an anatomical landmark for the CVC insertion may have a low success rate in children due to the positional variation between the deep vein and the landmarks, the small size of body and blood vessels, low insertion frequency, and operator skill. In order to improve the success rate, ultrasound guided CVC insertion is recommended in critically ill children. It is also expected to reduce mechanical complications, which are more common with subclavian CVC insertion. However, the association between the insertion site and the infection or thrombosis is unclear. Since thrombosis is relatively common, further studies are needed on the association between the incidence rate and insertion sites.