Breast cancer is a common manifestation of an underlying genetic susceptibility to cancer, and 5% to 10% of all breast cancers are associated with a germline mutation in a known risk allele. Detection of mutations has implications for targeted screening and prevention strategies for probands, and for genetic counseling and testing of their family members. This report presents a case involving a 35-year-old woman with no family history of breast or ovarian cancer who presented with a palpable right breast lump. Imaging revealed multiple bilateral breast masses and right axillary adenopathy, and core needle biopsies showed invasive ductal carcinoma in both the right and left breast. This report discusses the appropriate genetics evaluation for a patient with bilateral breast cancer at a young age, including testing for mutations in BRCA1 and BRCA2 (BRCA1/2), followed, if negative, by consideration of testing for mutations in TP53 (Li-Fraumeni syndrome). Given the specialized counseling and testing needs of patients with Li-Fraumeni syndrome, and the implications for targeted screening strategies if a mutation is found, referral to a cancer genetics expert is strongly recommended.