The annual incidence of acute pancreatitis (AP) per 100,00 people has increased from 15.6 in 1995 to 19.4 in 2000. Gender distribution revealed male predominance in patients aged between 30 and 60. AP has diverse etiologies. Alcohol consumption and gallstones were the main contribution factors. Due to advanced diagnostic equipments and techniques, the percentage of AP owing to miscellaneous and idiopathic causes has decreased significantly. The mortality rate of AP was 3% in 1980s, 4.4% in the early 1990s, and 2.1% in the late 1990s in Korea. During the late 1990s, the mortality rate has decreased even though the percentage of severe form has increased. This may be partly due to recent advances in medical management. Currently, there is no specific treatment capable of preventing complications of AP. Therefore, it is important to identify patients with severe AP using multiple clinical criteria, CT scans, and laboratory criteria. Close surveillance is necessary for patients with severe AP in order to identify and treat potential complications such as hemorrhage, shock, multiorgan failure as well as infection. Despite our thorough work-up using advanced diagnostic techniques, about one-fifth of the patients remain "idiopathic". As our understanding of AP improves and more advanced endoscopic and imaging techniques become available, this number will continue to decline.