...The extra-media thickness (EMT) is a composite measure of the arterial adventitia, PVAT and the jugular vein, but the association among EMT and aging, blood pressure and arterial stiffness is largely unknown. We hypothesized that EMT is associated with aging, blood pressure and arterial stiffness. Fifty (18M/32F, age range 20-79 yrs.) individuals underwent measures of EMT (ultrasonography), blood pressure (brachial; carotid), arterial stiffness (carotid beta-stiffness, distensibility, and Young's modulus), and body composition (dual x-ray absorptiometry). Independent two-tailed t-tests compared characteristics between young and middle-aged/older adults (MA/O). Bivariate correlations assessed the relation between EMT, aging, blood pressure and arterial stiffness endpoints. Partial correlations were used to adjust for age, sex, body mass index (BMI), and body fat percentage. Compared to young, MA/O adults had higher EMT, blood pressure, arterial stiffness, BMI, and BF% (all, p≤0.05). Carotid EMT was positively correlated with age (r=0.46), brachial SBP (r=0.32), carotid SBP (r=0.42), PP (r=0.42), beta-stiffness (r=0.37) and Young's elastic modulus (r=0.43) (all, p≤0.05), and negatively correlated with carotid distensibility (r=-0.34, p≤0.05). All endpoints correlated with EMT remained after adjusting for BMI, BF%, and sex (p≤0.05). No endpoints were correlated after further adjusting for age (p≥0.05). These data suggest EMT is a clinically relevant target that may be associated with age-related CVD risk in humans, yet further investigation is required to elucidate the role of EMT in age-related increases in blood pressure and arterial stiffness.