African American (AA) women have an elevated risk of cardiovascular disease and have been reported to have lower cardiorespiratory fitness (CRF) compared to Caucasian Americans (CA) women. However, little data exist evaluating racial differences in the change in CRF following aerobic exercise training. CA (n=264) and AA (n=122) postmenopausal women from the Dose Response to Exercise in Women study were randomized to 4, 8, 12 kilocalories per kg body weight per week (KKW) of aerobic training or the control group for six months. Cardiorespiratory fitness was evaluated using a cycle ergometer. A greater increase in relative CRF was observed in CA compared to AA women in the 4 (CA: 1.00 vs. AA: 0.35 mL O2*kg-1*min -1, p=0.034), 8 (CA: 1.59 vs. AA: 0.82 mL O2*kg-1*min -1, p=0.041) and 12KKW (CA: 1.98 vs. AA: 0.50 mL O2*kg-1*min -1, p=0.001) groups. Similar effects were found in absolute CRF with the exception of the 4KKW (CA: 0.04 vs. AA: 0.02, L O2/min, p=0.147) group. However, in categorical analyses, the percentages of women who improved both relative (>0 mL O2*kg-1*min -1) and absolute (>0 L O2/min) CRF were not significantly different for CA and AA participants in all exercise groups (all p>0.05). AA postmenopausal women in general had an attenuated increase in CRF (both relative and absolute) following exercise training, but had similar response rates compared to CA women. Future studies should investigate the physiologic mechanisms responsible for this attenuated response.