In recent years, testing for cancer susceptibility genes has entered the clinical setting. The practicing physician needs to be familiar with this evolving area of medicine to be able to counsel and/or refer high-risk patients such as those with a strong personal or family history of cancer. The following is a review of the clinically pertinent information regarding hereditary breast and ovarian cancers resulting from mutations in BRCA genes. A special emphasis is placed on the different options available for BRCA mutation carriers, because many interventions have already proven to be highly efficacious. The increased risk of cancer seen in hereditary nonpolyposis colorectal cancer (HNPCC) is not part of this review but is mentioned briefly.