Women with BRCA-1 or BRCA-2 mutations have a significantly increased risk for breast cancer. While genetic testing can provide valuable information concerning this increased risk and the proposed benefit of risk-reducing interventions, the absolute breast cancer risk conferred by BRCA-1 and BRCA-2 mutations remains to be fully determined. The American Society of Clinical Oncology (ASCO) guidelines indicate that testing should be considered in women whose mutation probability is greater than 10%. None of the currently available approaches for determining BRCA gene mutation probability are 100% accurate. The computer program BRCAPRO is a useful adjunct for estimating these probabilities, but limitations inherent in mathematical models make it essential that genetic counselors are involved in decisions to perform genetic testing.