As yet no clear criteria are available for differentiation of normal f
rom abnormal abdominal aortic diameter in relation to the development
of aortic aneurysm. The purpose of this study was to elucidate the age
-related changes in the abdominal aortic diameter. A total of 194 indi
viduals (97 men and 97 women) aged twenty years or more with no abnorm
alities in the abdominal aorta on physical examination were measured b
y B-mode two-dimensional ultrasonography for the maximum anteroposteri
or diameter of the abdominal aorta. Results were as follows: 1. A mult
iple regression analysis demonstrated that the age, height, and body w
eight were factors influencing the aortic diameter. The most significa
nt factor among them was the age (the partial correlation coefficient
was +0.811, P<0.01), and the next was the height (the partial correlat
ion coefficient was +0.453, P<0.01). 2. The relationship between the d
iameter and the height was evaluated by stratification of the subjects
at ten-year intervals. The correlation coefficients showed significan
t positive correlations observed in all age groups (P<0.001). 3. The r
elationship between the diameter and the age was studied according to
the height by dividing the subjects into five height groups. The corre
lation coefficients showed significant positive correlations observed
in all height groups (P<0.001).