Patterns of conduit artery shear are an important determinant of vascular function and increases to retrograde and oscillatory shear are associated with endothelial dysfunction, a key antecedent to atherosclerosis and cardiovascular disease. The adoption of this pro‐atherogenic profile described in humans is linked to chronological aging, and more recently, reproductive aging in women. To assess the potential influence of acute and chronic estrogen deficiency on arterial shear patterns, we studied premenopausal women (n=8, 22 ± 2 years) during the early follicular (Estradiol: 27.7± 9.2 pg/mL) and late follicular phase (Estradiol: 173.7 ± 144.3 pg/mL) of the menstrual cycle, and postmenopausal women (n=14, 60 ± 2 years, Estradiol: 22.3 ± 5.9) who were not on hormone therapy. Resting measures of brachial artery blood velocity and diameter were collected with Doppler ultrasound to determine mean, antegrade, and retrograde shear rates. Oscillatory shear index (OSI) was determined as the ratio between retrograde and antegrade shear rate. In premenopausal women, retrograde shear (−8.1 ± 2.8 vs. −7.6 ± 2.7 s−1, p=0.67) and OSI (0.07 ± 0.02 vs. 0.06 ± 0.03 a.u., p=0.89) were similar between menstrual phases, however these measures during both phases were significantly lower than in postmenopausal women (−13.3 ± 5.1 s−1, 0.21 ± 0.12 a.u., both p<0.05). These findings suggest that patterns of brachial artery shear remain stable across the menstrual cycle, despite fluctuations in estradiol. However, with prolonged estrogen deficiency secondary to menopause, retrograde and oscillatory shear are increased in the brachial artery, which likely contribute to endothelial dysfunction in postmenopausal women.Support or Funding InformationPenn State Jaffe EndowementThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.