Recognizing the limitation of the Atlanta classification for acute pancreatitis (AP), two international classifications have been recently proposed; the revised Atlanta classification and the determinant-based classification. There is an inconsistency between the two international classifications on whether infected necrosis (IN) is the major determinant of severity in AP. The aim of the current study was to validate the revised Atlanta classification and to determine the association of this new classification system with relevant clinical outcome in patients with AP.