Our aim was to determine if women who regularly perform endurance exercise demonstrate age-related elevations in body mass and adiposity. Ninety-five healthy females were studied: premenopausal ( n = 28; mean ± SE age 30 ± 1 yr) and postmenopausal ( n = 31; 56 ± 1 yr) endurance-trained runners and premenopausal ( n = 17; 29 ± 1 yr) and postmenopausal ( n = 19; 61 ± 1 yr) sedentary controls. In the runners, body mass did not differ across age, but percent fat and fat mass were higher ( P < 0.05) in the postmenopausal women. The age-related difference in total body fat, however, was only ∼50% as great ( P < 0.01) as that observed in the sedentary controls due in part to smaller age-related differences in central (truncal) fat. The higher fat mass in the postmenopausal runners was modestly (inversely) related to both exercise volume ( r = −0.44, P < 0.01) and maximal oxygen consumption ( r = −0.41, P < 0.01). The present findings provide experimental support for the hypothesis that women who regularly engage in vigorous endurance exercise may not gain body weight, undergo only a modest increase in total body fat, and do not demonstrate a significant elevation in central adiposity with age.