Until recently, pancreatic cancer was a poorly understood disease. Research in the past decade has shown conclusively, however, that pancreatic cancer is primarily genetic in nature. Inactivation with a variety of tumor-suppressor genes such as p16, DPC4, and p53, coupled with activation of oncogenes such as K-ras, are a few of the mutations that trigger the growth of cancerous cells. Understanding these mutations is critical to a better understanding of familial pancreatic cancer and to the development of gene-based screening tests and therapies. In this article, we review the genetic alterations identified in pancreatic cancer and provide examples of how this information can be applied to patient care.