We examined both jugular veins of 120 healthy subjects (60 men, 60 women; age range: 18 to 90 years); thus, a total of 240 jugular veins were examined. The vessel diameter was measured by color Doppler ultrasonography, and when valves were present at the ostial level, their morphology and competence were assessed. A single valvular apparatus was detected in 206 cases (86%). It consisted of 2 cusps in 75% of these 206 cases, of one in 15%, and of three in 10%. No correlations with side or the subjects' sex, age, height, or body weight were observed. In the 34 cases in which a valvular apparatus was not visualized, we found a male predominance (22 men as compared to 12 women). The mean diameter of the jugular vein at the ostial level was 13.8 mm, with that of the men being significantly larger than that of the women (p < 0.01), and it showed a tendency to increase with age. The valves were observed to be incompetent in 95% of the cases.