Almost all studies on post-ERCP pancreatitis (PEP) have mainly involved patients with biliary diseases rather than chronic pancreatitis (CP), and the concept that CP seems to be a protective factor associated with PEP has not been studied in detail. The aim of this study was to determine the incidence of PEP in patients with CP at different clinical stages and to identify the predictive and protective factors of PEP in a large cohort.