Heredity.net is a genetic counseling tool for hereditary breast cancer. Despite the fact that most women with a family history of breast cancer are not likely to carry a BRCA1 or BRCA2 mutation, studies show that this group is extremely interested in obtaining genetic testing. Other evidence indicates that these women also have exaggerated perceptions of their own risk for the disease. This can lead to increased anxiety and unwarranted requests for genetic testing. Of particular concern is the possibility that high demand for testing may exceed available counseling resources. Because of the anticipated high demand and limited counseling resources, there is a need for an educational tool to facilitate risk comprehension and informed decision making. Heredity.net is such a tool. As a proof of principle, we evaluated the application’s effectiveness in communicating the risk for hereditary breast cancer in a sample of 82 women who had a family history of breast cancer in at least one first-degree relative. We demonstrated that the Website was more effective than print media in improving risk comprehension for hereditary breast cancer. Subjects greatly exaggerated their personal risk for developing breast cancer at baseline. After using the Website, women became more accurate in their risk comprehension relative to those who relied on printed information.