Cardiovascular diseases (CVD) are the leading cause of mortality in the United States. Aging is the major risk factor for CVD development, which is independently predicted by arterial stiffness (AS). Arterial stiffening is closely related to age-related arterial structural/functional changes and obesity. Therefore, obese middle-aged and older adults are considered a high CVD risk population. In light of the current obesity epidemic and the projected growth of the older population, there is an overwhelming need to determine if weight loss (WL) may reduce AS (CVD risk) in this population. Thus, we hypothesized that WL via a hypocaloric diet-alone would reduce AS in overweight and obese middle-aged and older adults. To test our hypothesis, baseline assessment of anthropometrics, blood pressure and AS was conducted, and subjects were randomized to a 12-week WL intervention or a control group. Arterial stiffness was measured using applanation tonometry to estimate carotid-femoral artery pulse wave velocity (C-F PWV), and with high-resolution ultrasonography of the carotid artery (β-SI). There were no baseline differences between groups in our variables of interest. Consistent with our hypothesis, both measures of AS were significantly reduced (C-F PWV= -16% and β-SI= -12%, P<0.05) with WL (-8%, P<0.05). Weight loss also resulted in significantly decreased blood pressure, total body and abdominal fat. No such changes were observed in the control group. Pooled correlation analysis suggests that the magnitude of change in C-F PWV was not associated with changes in systolic, diastolic or mean blood pressure. We further hypothesized that reductions in AS, if observed, would be associated with the magnitude of reduction in total body or abdominal adiposity. Concordant with our hypothesis, the reductions in C-F PWV were significantly associated with total and abdominal fat. However, linear regression analysis indicate that neither total body nor abdominal body fat were capable of independently predicting reductions in C-F PWV. Our findings suggest that moderate WL in overweight and obese middle-aged and older adults is an efficacious treatment strategy for reducing AS. Further studies are needed to determine if the improvements in arterial compliance would be sustained with long-term WL maintenance.