Purpose: The aim of this study is to determine the optimal angle of needle entry in the sagittal plane for internal jugular vein (IJV) catheterization with the central approach while the head is in the neutral position. Methods: The contrast-enhanced carotid artery computed tomography angiographies of 123 consecutive patients were retrospectively reviewed. The point of merger between the sternal and clavicular heads of the sternocleidomastoid muscle was assumed as a clinical entry (CE) point. The angle between CE point and the center of the IJV, the depth, diameter of the vessels and the degree of overlap between the IJV and carotid artery (CA) were measured. Results: The angles between the CE point and the center of the IJVs were similar, 7° ± 13° medial and 8° ± 12° medial on the right and the left side, respectively. The center of IJVs from the CE point was between 0° and 16° toward the medial in 79.8% on the right side and 89.9% on the left side of patients. The diameters of the right IJVs were greater than the left IJVs (p = 0.001). The depth from the skin and overlap between IJV and CA did not vary between the two sides. Conclusions: When a central approach is used for right internal jugular vein (RIJV) cannulation with a neutral head position, the orientation of the angle of needle entry (i.e., 16°) medially in the sagittal plane may quadruple the success rate of RIJV catheterization compared to the success rate of a laterally oriented angle of entry as recommended by the classic method. Copyrigh © Informa Healthcare USA, Inc.