Background/Aims: In recent years, the incidence of acute pancreatitis (AP) has been increasing. A better understanding of the etiology is directly linked to more favorable outcomes. Unfortunately, there have been reports suggesting the variation of etiologies of AP across countries. The objective of this study was to determine the etiology of AP in a general hospital of Seoul-Gyeonggi province in Korea during the past decade. Methods: We retrospectively reviewed the medical records of consecutive patients with AP who were admitted to St. Paul's Hospital (Seoul, Korea) with an affiliation to the Catholic University of Korea between January 2003 and January 2013. Results: A total of 1,110 patients were enrolled, totaling 1,833 attacks, and the most frequent cause of AP was alcohol consumption. The recurrence rate of AP was 24.5% (272/1,110), and habitual recurrence rate (more than three times) was 12.6% (140/1,110). The rate of severe AP was 4.9% (90/1,833 attacks). The mortality rate of AP was 2.6% (29/1,110 patients). The frequency of an idiopathic cause of AP was 13.3%. The recurrence rate and mortality rate of idiopathic AP were 16.2% and 5.4%, respectively. In 41.7% (10/24) of cases of idiopathic AP, microlithiasis was suspected. Conclusions: Between 2003 and 2013 in Korea, alcohol was the most frequent cause of AP in the general hospital of Seoul-Gyeonggi province of Korea. It appears that alcohol abstinence program may be necessary. Further nationwide studies would be needed to evaluate the etiologies of AP. (Korean J Gastroenterol 2017;70:190-197)