Estimate the prevalence and identify risk factors for bone loss in women with BRCA mutations. Women, age 40 and older, with BRCA mutations identified from the Breast Cancer Surveillance database at Kaiser Permanente Northern California were invited to participate and undergo a dual-energy x-ray absorptiometry scan to assess for bone loss (osteopenia or osteoporosis). Multivariable logistic regression analysis was performed to assess clinical factors associated with bone loss. Of the 238 women in the final cohort, 20 women had intact ovaries (median age 54.5years) and 218 had undergone risk reducing salpingo-oophorectomy (RRSO) (median age 57). The prevalence of bone loss was 55% in the no RRSO group and 72.5% in the RRSO group (P=0.10). In multivariable analysis, only higher body mass index (OR 0.6 per 5kg/m2, 95% CI: 0.4-0.7) and nonwhite race compared to white (OR 0.5, 95% CI: 0.2-0.9) were protective for bone loss while older age (OR 1.5 per 10years, 95% CI: 1.1-2.1) and selective estrogen receptor modulator use (3.1, 95% CI: 1.2-10.1) were associated with increased odds of bone loss. Among women with RRSO, bone loss was more frequent in women who had postmenopausal (n=106) compared to women who had premenopausal RRSO (n=112), (82.1% and 63.4% respectively, P=0.002). In multivariable analysis, only BMI was protective of bone loss (OR 0.5, 95%, CI: 0.4-0.7) but neither age nor menopausal status at RRSO were associated with bone loss. Bone loss is common in women with BRCA mutations who undergo RRSO.