Introduction: Black women develop hypertension (HTN) earlier in life and experience higher cardiovascular disease (CVD) morbidity and mortality rates at younger ages compared to White women. Growing evidence suggests this may be due to Black women experiencing premature physiological deterioration and accelerated biological aging, true global state of an aging organism. Yet, the relationship between biological aging and arterial stiffness, a precursory marker of subclinical CVD, in Black women has not been studied. We investigated the association between biological age (BA) and arterial stiffness in Black and White women. Hypothesis: BA will be associated with arterial stiffness and this association will be modified by race. Methods: In 219 women (n=140 White, n=79 Black) enrolled in the Morehouse-Emory Center for Health Equity and Predictive Health Institute cohorts (age range 25-49), arterial stiffness was assessed using carotid-femoral pulse wave velocity (CFPWV), measured by applanation tonometry (SphygmoCor®). BA was estimated using the Klemera-Doubal method from 10-select clinical biomarkers (BUN, Creatinine, Total Cholesterol, Alkaline Phosphatase, MCV, RDW, Albumin, Lymphocytes, WBC, CRP) and chronological age. Overall and race-specific associations between BA and arterial stiffness adjusting for demographics (race, education, income, marital status), lifestyle (alcohol, smoking), clinical (body mass index, HTN, diabetes history, SBP), and mental health factors (depressive symptoms) were estimated using multiple linear regression. Results: Mean chronological and BA age was 40 (SD=6.1) and 43 (SD=7.2) years, respectively. Black women had a BA that was 3.4 (SD=5.7) years older than their chronological age, while the difference was 1.3 (SD=4.8) years older for White women. Thus, Black women’s BA was 2.1 (95%CI: -3.5, -0.6) years older than White women. Mean (SD) CFPWV was 7.3 (1.1) in Black women and 6.3 (0.8) in White women. Overall, BA was associated with higher (worse) CFPWV in the minimal (β=0.06 m/s per year, 95%CI: 0.03, 0.08) and fully adjusted models (β=0.04 m/s, 95%CI: 0.01, 0.08). There was no significant interaction between race and BA in the association with arterial stiffness. Conclusions: Black women had older BA and worse CFPWV than White women. BA may partially account for the higher arterial stiffness in Black women.