Since Sarles et al. in 1961 reported a particular type of pancreatitis with hypergammaglobulinemia, many investigators have suggested that an autoimmune mechanism may be involved in some patients with pancreatitis. Recently, the concept of autoimmune pancreatitis (AIP) has been proposed in which several unique clinical, biochemical and imaging signs have been shown. In the TIGARO risk factor classification system of chronic pancreatitis proposed in 2001, autoimmunity was categorized as one of six of the risk factors. AIP is a chronic fibroinflammatory condition primary affecting pancreas. It is an atypical form of chronic pancreatitis characterized by sonolucent swelling of the pancreas, diffuse irregular narrowing of the pancreatic duct, and high serum IgG4 concentrations. Co-occurrence of extrapancreatic involvement, such as sclerosing cholangitis, retroperitoneal fibrosis, or salivary gland swelling were found: Histopathologic examinations detected extrapancreatic lesions such as lymphoplasmacytic inflammation and fibrosis, similar to those present in the pancreatic tissue, suggesting a common pathogenesis. These findings suggest that the disease involves a general involvement of the digestive system, although the presence of such involvement has not been fully elucidated. Steroids are a main therapeutic option in AIP.