Aim: Ultrasound assessment of morphological parameters of the internal jugular veins and vertebral veins in healthy individuals as well as their dependence on the patient’s position. Material: The examinations were conducted in 185 healthy individuals (101 females and 84 males) aged 18–89. Ultrasound examinations were conducted with the use of a linear probe with the frequency of 5–9 MHz in the supine (0°) and sitting position (90°). Results: In 154 cases (83.2%) on the left side and in 150 cases (81.1%) on the right side, the jugular veins were completely closed in the sitting position. In 31 cases (16.8%) on the left side and in 35 cases (18.9%) on the right side, they were merely narrowed. By contrast with the jugular veins, the cross-sectional area (CSA) of the vertebral veins was greater in the sitting position than in the supine position in a statistically significant way. The CSA values of the jugular veins in the supine position ranged from 0 cm2 to 4.3 cm2. There were no statistically significant differences in the CSA between men and women. The cross-sectional area of the right jugular vein in the supine position was greater in a statistically significant way than that of the left jugular vein. In this study population, the ratio of the cross-sectional areas of the jugular veins on both sides amounted to 8.5:1. Conclusions: The width of the jugular and vertebral veins significantly varies depending on the patient’s position. The range of the CSA values for the jugular veins is broad, which should be taken into account when interpreting imaging findings. The internal jugular veins can show considerable asymmetry.