Autonomic nervous system (ANS) control of the circulation is altered with aging in adult humans. Similar changes are observed in obesity, particularly abdominal obesity. To determine if age-associated differences in ANS-circulatory function can be partially explained by increased body fatness, we examined ANS function and 3 expressions of adiposity (total body fat, abdominal body fat, and abdominal-to-peripheral body fat distribution--dual-energy x-ray absorptiometry) in 43 healthy men: 27 young (25±1 yr) and 16 older (65±1). ANS functions assessed included: 1) autonomic support of arterial blood pressure (BP; radial artery catheter), i.e., the reduction in BP during vs. before acute ganglionic blockade (GB; intravenous trimethaphan); 2) baroreflex buffering, i.e., the increase in systolic BP with continuous incremental and bolus infusions of phenylephrine during vs. before GB; 3) cardiovagal baroreflex sensitivity (Oxford technique); and 4) heart rate variability (time and frequency domain analyses). Covarying for abdominal-to-peripheral fat distribution reduced or abolished age-related differences in ANS support of BP, cardiovagal baroreflex sensitivity, and heart rate variability but did not affect age-related differences in baroreflex buffering. Covarying for abdominal and total fat had small selective or no effects on ageassociated differences in autonomic-circulatory control. Abdominal-to-peripheral fat distribution explains a significant portion of the variance in a number of autonomic-circulatory functions attributable to aging. Therefore, the development of this fat pattern may contribute to several changes in ANS-cardiovascular function observed with aging. These results may help explain how changes in body fat distribution with advancing age are linked to impairments in circulatory control.