Cancer genetics has rapidly evolved in the last two decades. Understanding and exploring the several genetic pathways in the cancer cell is the foundation of targeted therapy. Several genomic aberrations have been identified and their role in carcinogenesis is being explored. In contrast to most cancers where these mutations are acquired, patients with hereditary cancer syndromes have inherited genomic aberrations. The understanding of the molecular pathobiology in hereditary cancer syndromes has advanced dramatically. In addition, many molecularly targeted therapies have been developed that could have potential roles in the treatment of patients with hereditary cancer syndromes. In this review, we outline the presentation, molecular biology, and possible targeted therapies for two of the most widely recognized hereditary cancer syndromes -- hereditary breast and ovarian cancer syndrome and hereditary non-polyposis colorectal cancer syndrome (Lynch syndrome). We will also discuss other syndromes such as familial adenomatous polyposis and Li-Fraumeni syndrome (TP53).