The internal jugular vein is often used for central venous catheter placement. The variations in the location of this vein along the major neck vessels (in the carotid sheath) may account for unsuccessful cannulations or iatrogenic arterial injuries. The aim of this study was to delineate the relation of the internal jugular vein and common carotid artery in the lower neck, and to assess the effects of age, gender and side on these anatomical structures. Two-dimensional ultrasonographic examinations of the right and left supraclavicular triangle were performed in 219 adult individuals who had no history of neck surgery or known pathology. The location of the internal jugular vein in relation to the common carotid artery was recorded. An anterolateral location of the internal jugular vein was the most common configuration observed on both sides (84% right side and 91.8% left side) followed by the lateral (14.2% right and 6.4% left) and anterior (1.4% right and 1.8% left) locations. A single case of a medial internal jugular vein was observed on the right side (0.23% of both sides). Subjects with a laterally located internal jugular vein were older than those with an anterolateral configuration (P<0.01). No gender differences were found with regard to these two configurations (P=0.867). The laterally located internal jugular vein was more frequent on right sides (P=0.007). Such information may be potentially useful for clinicians who are managing critically ill patients or patients undergoing hemodialysis.