Aim: To compare clinical aspects between biliary and alcoholic acute pancreatitis (AP). Methods: All patients with AP from August 2003 to October 2005 were included in this prospective protocol, which was approved by the Ethical committee from the Hospital. We compared clinical features between the patients with biliary and alcoholic etiology. The patients with gallstones that had a regular intake of alcohol were excluded of this study. Chi square and Student’s t test were used for statistical analysis, considering p < 0.05 as significant. Results: We obtained 162 patients with AP in this period, with the following etiologies: gallstones in 90 (55.6%) patients, alcohol in 49 (30.2%), idiopathic in 12 (7.4%), hyperlipidemia in 3 (1.9%), and 8 (4.9%) patients had gallstones and regular alcohol intake history. We observed differences between the biliary and alcoholic groups regarding to gender and previous episodes of pancreatitis (Table 1). Furthermore, amylase was not able to confirm the diagnosis of AP in 10% of patients with biliary etiology and in 59.2% of patients with alcoholic etiology, while 17 (18.9%) patients with gallstones and 5 (10.2%) with alcoholic etiology had lipase increased less than 3 times (p=n.s.). AST, ALT, AP and GGT were significantly higher in the biliary group. We have also found an increase in the levels of hemoglobin and creatinin, and a decrease in the bicarbonate levels in the alcoholic patients when compared with the biliary group. There were no differences in severity, morbidity and mortality between the groups. Conclusion: We conclude that lipase play a role in the diagnosis of AP in patients with alcoholic etiology. Although we haven’t found differences in morbidity and mortality, the patients with alcoholic etiology appear to be more dehydrated on admission, requiring a more vigorous fluid replacement.