OBJECTIVES: We sought to examine temporal trends in incidence and outcomes of acute pancreatitis (AP) in hospitalized adult patients in the United States. METHODS: Subjects were obtained from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample database using International Classification of Diseases, Ninth Revision, Clinical Modification codes for the years 2002-2013. Incidence of AP, all-cause mortality, cost, and duration of hospitalization were assessed. RESULTS: We identified 4,791,802 cases of AP. A significant increase in the incidence of AP was observed from 9.48 cases per 1000 hospitalizations in 2002 to 12.19 per 1000 hospitalizations in 2013 (P < 0.001). In-hospital mortality decreased from 2.99 cases per 100 cases in 2002 to 2.04 cases per 100 cases in 2013 (P < 0.001). Mean length of stay decreased from 6.99 (standard deviation [SD], 9.37) days in 2002 to 5.74 (SD, 7.94) days in 2013 (P < 0.001). Cost of hospitalization increased from $27,827 (SD, $54,556) in 2002 to $49,772 (SD, $106,205) in 2013 (P < 0.001). CONCLUSIONS: Hospital admissions for AP in adults increased significantly in the United States from 2002 to 2013. In-hospital all-cause mortality and mean length of stay significantly decreased. In contrast, total cost of hospitalization rose.