Background In this study, we aimed to compare differences in disease course, etiology of acute pancreatitis admission to the intensive care unit, in-hospital mortality, disease severity, and local and systemic complications between patients aged >= 80 years (octogenarians) and patients aged between 65 and 79 years (non-octogenarians), all of whom were being followed with the diagnosis of acute pancreatitis. Methods Patients aged 65 years and older with a diagnosis of acute biliary pancreatitis were included in the study. Clinical findings, routine laboratory test results, and imaging findings of all patients were reviewed retrospectively via the hospital's records system. Results Of a total of 402 enrolled patients, 238 (59.2%) were female. Mean age was 77.1 +/- 7.37 years. Pancreatitis after endoscopic retrograde cholangiopancreatography was detected more frequently among octogenarians than non-octogenarians (12.9% versus 5.3%, respectively; p = 0.007). Levels of blood urea nitrogen, creatinine, and total bilirubin were higher among octogenarians, while lymphocyte, calcium, and albumin levels were lower. The frequency of patients without local complications was higher among octogenarians than non-octogenarians (75.5% versus 63.6%, respectively; p = 0.013). Necrosis was less frequent in the octogenarian group than the non-octogenarian group (2.6% versus 8.9%, respectively; p = 0.012). Mild acute pancreatitis was higher in the octogenarian group, while moderate acute pancreatitis was higher in the non-octogenarian group (p = 0.028 and p = 0.012, respectively). Conclusion The frequencies of prolonged hospitalization, intensive care unit admission, and in-hospital mortality were similar in the octogenarian and non-octogenarian groups. In terms of disease severity, mild acute pancreatitis was higher in the octogenarian group, while moderate acute pancreatitis was higher in the non-octogenarian group. Key summary pointsAim This study aims to identify differences between octogenarian (patients over 80 years old) and non-octogenarians (patients between 65 and 79 years old) in the course of acute pancreatitis. Findings The incidence of local complications was higher in the non-octogenarian group. Mild acute pancreatitis was higher in the octogenarian group, while moderate acute pancreatitis was higher in the non-octogenarian group. There was no significant difference compared to severe cases. Message Contrary to what was expected, no significant difference was observed between the octogenarian and non-octogenarian groups in terms of serious events in the course of acute pancreatitis.