BACKGROUND Autoimmune pancreatitis (AIP) is a unique chronic inflammation of the pancreas in which autoimmune mechanisms are involved in the pathogenesis. It is characterized by clinical, histopathological, radiographic, serologic and therapeutic features. Since it was first described in 1995, increasing numbers of AIP patients have been diagnosed. METHODS In this study, the data from 2 patients with AIP who had elevation of serum immunoglobulin G, positive autoantibody, swelling of the pancreas and narrowing of the main pancreatic duct on imaging were analyzed retrospectively. RESULTS With the initial diagnosis of AIP, both patients underwent regular prednisone therapy, which was initiated at a dose of 40 mg per day with a tapering schedule of 5 mg every 2 weeks. The patients responded very well to treatment with prednisone. CONCLUSIONS AIP is a relatively new disease entity. Although it is diagnosed by distinct characteristics of the clinical, radiologic, histopathologic, and serologic findings, many questions require further clarification, including its relationship to other autoimmune diseases and misdiagnosis as pancreaticobiliary malignancies.