Inclusion Criteria:  18 years old or older Hospital admission due to acute pancreatitis (definition: at least 2 of the following criteria: A) Typical pancreatitis pain, B) Amylase and/or lipase higher than 3 times the upper level of normality, C) Imaging compatible with acute pancreatitis Presence of gallstones according to any imaging technique Patient informed consent  Exclusion Criteria:  Cholecystectomy and/or endoscopic retrograde cholangio-pancreatography and / or endoscopic cholecystostomy prior to recruitment Recurrent acute pancreatitis (1 or more previous episodes of pancreatitis of any origin) Current waiting list for cholecystectomy for acute biliary pancreatitis at that center less than 30 days Randomization more than 3 days after hospital discharge for acute pancreatitis Ursodeoxycholic acid (UDCA) consumption in the last 5 years or previous UDCA failure to dissolve lithiasis Allergy, intolerance or presence of contraindications to UDCA (contraindicated in patients with active gastric or duodenal ulcer, liver or intestinal disorders that interfere with the enterohepatic circulation of bile salts and lactation) Presence of choledocholithiasis diagnosed by imaging tests prior to randomization Active alcoholism greater than or equal to 5 daily alcoholic drinks in men or 3 in women or high clinical suspicion of clinically significant alcoholism Recent history of significant therapeutic non-compliance or social problem that makes follow-up difficult Hypertriglyceridemia greater than 400 mg / dL during admission or history of poorly controlled severe hypertriglyceridemia Chronic pancreatitis (pancreatic calcifications and / or Wirsung duct 4 or more mm) Pancreatic cystic lesions not attributed to the pancreatitis itself Wirsung duct stenosis Primary hyperparathyroidism Pregnancy