Autoimmune chronic pancreatitis (AIP) can be defined as a chronic inflammation of the pancreas due to an autoimmune mechanism; autoimmunity is responsible for producing the pancreatic lesion. AIP is a distinctive type of chronic pancreatitis that shows reversible improvement of pancreatic morphology and function with oral steroid therapy, in comparison to other types of chronic pancreatitis which hardly respond to various treatments. AIP is increasingly being recognized to be a worldwide entity. The sudden increment in cases reported probably reflects the growing awareness of the entity, rather than a rise in the true incidence. In previous Japanese report, HLA DRB1*0405-DQB*0401 haplotype may be associated with autoimmune pancreatitis in the Japanese population. However, to date there was no subsequent data for supporting these results. In addition, this Japanese study had a limitation in methodology by using a low-resolution typing for HLA. Although this entity is well responsive to steroid therapy, relapse of AIP during steroid treatment is not uncommon. Unfortunately, there has been no laboratory or genetic predictor for responsiveness to steroid therapy in patients with AIP. To further clarify and confirm high-risk and protective genotypes for autoimmune diseases, therefore, high-resolution typing for HLA should be needed. Thus, to determine whether certain alleles or haplotypes of major histocompatibility complex gene are associated with AIP in Korean population, we undertook this study with high-resolution typing for HLA (sequence-based typing).