The purpose of this study was to investigate the occurrence of gallstones and the severity of acute pancreatitis in a Danish population, and in severe cases, the relation between pancreatic necrosis and gallstones. We used Ranson's prognostic scoring system to measure the severity of acute pancreatitis, ultrasonography for detecting biliary stones, and computed tomography or laparotomy for detecting pancreatic necrosis. During a two year period, we registered 101 patients. Approximately 70% were mild cases, and we found 18 patients with and 53 patients without gallstones. Among patients with severe cases, we observed 14 with and 16 without gallstones. There was a significantly higher proportion of gallstones in severe cases. Eight of 30 patients with severe pancreatitis had pancreatic necrosis, but we found no relation between the occurrence of necrosis and gallstones. We conclude that patients with gallstone related pancreatitis have more severe disease than patients without stones, but the complication of pancreatic necrosis is not related to gallstones.