History, physical examination, simple laboratory and radiological tests, and endoscopic retrograde cholangiopancreatography (ERCP) are able to establish the cause of recurrent acute pancreatitis in 70% to 90% of patients. Dysfunction of the biliary and/or pancreatic sphincter, as identified by sphincter of Oddi manometry, accounts for the majority of the remaining cases. The diagnosis may be missed if the pancreatic sphincter is not evaluated. Pancreas divisum is a prevalent congenital abnormality that is usually innocuous but can lead to recurrent attacks of acute pancreatitis or abdominal pain. In select cases, endoscopic sphincterotomy of the minor papilla can provide relief of symptoms and prevent further attacks. A small proportion of patients with idiopathic pancreatitis have tiny stones in the common bile duct (microlithiasis). Crystals can be visualized during microscopic analysis of bile that is aspirated at the time of ERCP. Neoplasia is a rare cause of pancreatitis, and the diagnosis can usually be established by computerized tomography or ERCP. A wide variety of medications can also cause recurrent pancreatitis. ERCP, sphincter of Oddi manometry, and microscopy of aspirated bile should be undertaken in patients with recurrent pancreatitis in whom the diagnosis is not obvious.