As one of the most common conditions affecting the alimentary tract and the leading cause of gastrointestinal-related hospitalizations in the United States, acute pancreatitis (AP) is a major source of economic burden with an estimated cost of AP-related hospitalizations exceeding 2 billion dollars to the US healthcare system in 2009. Cases of AP occur with an incidence ranging between 15 and 45 cases per 100,000 patients in the United States and 5 and 73 cases per 100,000 patients globally, with an increasing incidence observed in recent years. Moreover, AP can have dramatic physical and psychological consequences on patients with subsequently decreased quality of life and economic hardship faced through prolonged and/or multiple hospitalizations. Despite advances in knowledge regarding the pathophysiology of AP and its medical management, overall population-level mortality rates resulting from AP have continued to remain stable. The purpose of this chapter is to review the etiology, pathophysiology, diagnostic evaluation, and medical management of AP.