Background The right internal jugular vein is commonly preferred for central venous cannulation, and ultrasonographic assessment and guidance is the recommended technique for this procedure. Despite the safety and reliability of this technique, it requires specific training and experience as well as thorough knowledge of anatomy. Aim The position of the right internal jugular vein with respect to carotid artery and its transverse diameter free from overlap with the carotid artery were evaluated using ultrasound in patients aged 0-2 years. Methods This single-center, prospective, observational study included patients aged 0-2 years who underwent elective surgery between July 2018 and July 2019. The diameters and anatomical position were evaluated using ultrasound. All parameters were compared between groups classified according to postmenstrual ages. The correlations of these parameters with weight and postmenstrual ages were analyzed. Results A total of 156 patients were included. The diameters (P < .001) and depth (P = .012) were smaller in patients with postmenstrual age <45 weeks. The anteroposterior diameter was significantly correlated with weight in patients with postmenstrual age <45 weeks, but not in older patients. Right internal jugular vein was lateral and anterolateral with respect to carotid artery in 51.3% and 42.9% of patients, respectively, and >80% of the transverse diameter was free from overlap with the carotid artery. Conclusion Our results support the current data for the high anatomical variability of the right internal jugular vein, highlighting the recommendation of the Rapid Central Vein Assessment (RaCeVA) protocol prior to and ultrasound guidance during catheterization of central veins.