Acquiring data about venous or arterial vessel size is important for several reasons, given the increasing incidence of thomboembolic phenomena and arterial aneurysms and the emerging new vascular techniques. We studied 250 healthy subjects (125 men and 125 women; age range: 50 to 91 years) with no known vascular pathology, nor hypertension, nor diabetes. We assessed the caliber of abdominal aorta, inferior vena cava, iliac and femoral arteries and viens by color doppler ultrasonography, and analyzed the results with regard to sex, height, weight and body surface of each subject. The mean caliber measure of the large abdominal vessels appeared lower than the value obtained from cadavers. There was a direct proportion between the left and right vessels of the same subject. The difference in vessel caliber between male and female subjects was statistically signifi cant. There was no correlation between vessel caliber and age, height or body surface area.