Biliary stones are the leading cause of acute pancreatitis. Although cholecystectomy and selective endoscopic retrograde cholangiography (ERC) comprise the current treatment in patients with acute biliary pancreatitis (ABP), the time of intervention is still controversial. In this study we evaluated the outcomes of cholecystectomy on first admission for ABP and in patients with recurrent biliary pancreatitis. A series of 43 patients with ABP between January 1997 and November 2000 were evaluated retrospectively. Patients were classified into two groups. Group I included 27 patients who underwent cholecystectomy on first admission before discharge from the hospital. Group II comprised 16 patients who had recurrent biliary pancreatitis and then underwent cholecystectomy. The severity of the pancreatitis was determined by Ranson's criteria. Age, gender, length of hospital stay, severity of pancreatitis, amylase level, and complications of cholecystectomy were evaluated in both groups. Patients in group I underwent cholecystectomy during the original hospital admission and patients in group II during an admission for a recurrence. There were 24 patients with a Ranson's score </= 3 in group I and 12 in group II. The mean hospital stays were 15.29 days (range 4-48 days) and 36.66 days (range 15-123 days) in groups I and II, respectively ( p = 0.006). Morbidity was 11% without mortality in group I and 43% with one mortality in group II ( p = 0.023). Definitive treatment of ABP can be accomplished effectively and safely by cholecystectomy following clinical improvement, with selective ERC performed during the first admission (delayed cholecystectomy). Waiting to perform cholecystectomy (interval cholecystectomy) may result in recurrent biliary pancreatitis, which may increase morbidity and the length of the hospital stay.