Female BRCA1/2 mutation carriers develop in up to 50% breast cancer (BC) before age 50 years. We investigated whether the specific histologic features of BRCA1/2-associated breast cancer influence imaging. We correlated the mammographic results with the histology of 34 BC in BRCA1/2 mutation carriers and 34 sporadic cancers in patients, matched for age and year of diagnosis. Mammography was significantly more frequently false-negative in carriers than controls (62% vs. 29% p = 0.01), despite comparable tumor size (mean ⊘ 1.51 vs. 1.75) and breast density (high 41% vs. 53%). The image in carriers was significantly less as spiculated mass (6 vs. 18 p = 0.01). Cancers of BRCA1/2 mutation carriers had frequently higher mitotic counts (p < 0.0001) and prominent pushing margins around the tumor (p = 0.08) (p = 0.05 for 32 BRCA1). We also observed that prominent “pushing margins” correlated significantly with a false-negative mammography (p = 0.005) and with a mammographic image of a smooth, not a spiculated, mass (p = 0.01). False-negative mammography correlated independently with: BRCA1/2 mutation (p = 0.02), prominent pushing margins (p = 0.03) and high breast density (p = 0.01). MRI was carried out in 12 carriers, had 100% sensitivity and detected 5 cancers, still occult at physical examination and mammography. A BRCA1/2 mutation and high breast density at mammography contribute independently to false-negative mammography results. In mutation carriers any mammographic mass must be regarded with suspicion. Pushing margins of the tumor partly explain these results. For early BC detection in mutation carriers additional methods like MRI may be needed. This may not be necessary in other young women with breast symptoms. © 2002 Wiley-Liss, Inc.