Young Black women in the United States are disproportionately afflicted with breast cancer, a proportion of which may be due to BRCA1 and BRCA2 (BRCA) gene mutations. In a cancer registry-based sample of young Black women with breast cancer, we evaluated: (1) the prevalence of BRCA mutations detected through full gene sequencing and large rearrangements testing and (2) proportions that accessed genetic services pre-dating study enrollment. Black women diagnosed with invasive breast cancer ≤age 50 years in 2009-2012 were recruited through the Florida Cancer Registry. Participants completed genetic counseling, a study questionnaire, and consent for medical record release. Saliva specimens were collected for BRCA testing. Overall, 13 participants (9 %) had BRCA mutations detected (including 11 through full gene sequencing and two through large rearrangements testing). One of these large rearrangements, BRCA1 (delExon8), was identified in a participant who had previously tested negative on clinical comprehensive BRCAnalysis that was performed prior to undergoing a lumpectomy. Although all 144 participants met national criteria for referral for cancer genetic risk assessment, 61 (42 %) were referred for genetic counseling and/or had genetic testing preceding study enrollment, and only 20 (14 %) received genetic counseling. Our findings emphasize the importance of large rearrangements testing to increase detection of deleterious BRCA mutations in young Black women with breast cancer. The registry-based design of our study increase the generalizability of findings compared with efforts focused on clinic-based populations. Furthermore, results suggest efforts are needed to improve access to genetic counseling and testing.