Plasma estradiol concentrations are typically elevated in obese African American women with upper body adiposity. Exercise may alleviate higher than normal estradiol concentrations. However, direct evaluations of plasma estradiol with ethnicity and adipose phenotype at rest and exercise in obese women are limited. PURPOSE: There were two purposes for the study: 1) to determine if a relationship exists between mean immediate-post exercise plasma estradiol concentrations and two predictor variables: ethnicity (African American and Caucasian) and adipose phenotype (lean, upper body adiposity, lower body adiposity), and 2) to determine if a relationship exists between mean resting plasma estradiol concentrations and two predictor variables: ethnicity and adipose phenotype. METHODS: Seventy-two women completed the study. We evaluated anthropometrics and estimated VO2max utilizing a treadmill and modified Balke protocol. Adipose phenotype was determined by the waist hip ratio and body mass index, while body fat percentage was determined via DXA on day 1. Plasma estradiol was measured at rest and immediate-post 30-minutes of walking at a moderate intensity (40-60% heart rate reserve) on day 2. RESULTS: Forward multiple linear regression indicated that ethnicity (E) and adipose phenotype (AP) did not predict immediate-post exercise (E, r = -.158; AP, r =.002) or resting (E, r = -.203; AP, r =.018) follicular-phase plasma estradiol concentrations. Further, ANCOVA analysis revealed no significant difference in immediate-post exercise or resting estradiol concentrations by ethnicity or adipose phenotype while controlling for resting plasma estradiol concentrations. CONCLUSION: A novel finding of this research revealed that immediate-post plasma estradiol concentrations were similar across the groups after moderate intensity exercise. Also, resting plasma estradiol concentrations were similar across the groups. Further research should examine the physiological response of plasma estradiol following moderate intensity endurance exercise in women who have been identified as possessing higher than normal plasma estradiol concentrations.