Background-Few studies have empirically tested the association of allostatic load (AL) with breast cancer clinicopathology. The aim of this study was to examine the association of AL, measured using relevant biomarkers recorded in medical records before breast cancer diagnosis, with unfavorable tumor clinicopathologic features among Black women.Methods-In a sample of 409 Black women with non-metastatic breast cancer, who are enrolled in the Women's Circle of Health Follow-Up Study (WCHFS), we estimated pre-diagnostic AL using two measures: AL measure 1 (lipid profile-based -assessed by systolic and diastolic blood pressure [SBP, DBP], high-density lipoprotein, low-density lipoprotein, total cholesterol, triglycerides and glucose levels, waist circumference, and use of diabetes, hypertension, or hypercholesterolemia medication) and AL measure 2 (inflammatory index-based -assessed by SBP, DBP, glucose and albumin levels, estimated glomerular filtration rate, body mass index, waist circumference, and use of medications described above). We used Cohen's kappa statistic to assess agreement between the two AL measures and multivariable logistic models to assess the associations of interest.