Neurofibromatosis type 1 (NF1) is one of the most common cancer predisposing syndromes with an incidence of 1 in 3,500 worldwide. Certain neoplasms or malignancies are over-represented in individuals with NF1; however, an increased risk of breast cancer has not been widely recognized or accepted. We identified 76 women with NF1 seen in the Henry Ford Health System (HFHS) from 1990 to 2009, and linked them to the Surveillance Epidemiology and End Results (SEER) registry covering the metropolitan Detroit area. Fifty-one women (67%) were under age 50 years at the time of data analysis. Six women developed invasive breast cancer before age 50, and three developed invasive breast cancer after age 50. Using standardized incidence ratios (SIRs) calculated based on the SEER age-adjusted invasive breast cancer incidence rates, our findings demonstrated a statistically significant increase of breast cancer incidence occurring in NF1 women (SIR = 5.2; 95% CI 2.4–9.8), and this relative increase was especially evident among those with breast cancer onset under age 50 (SIR = 8.8; 95% CI 3.2–19.2). These data are consistent with other reports suggesting an increase in breast cancer risk among females with NF1, which indicate that breast cancer screening guidelines should be evaluated for this potentially high-risk group. © 2012 Wiley Periodicals, Inc.