The present 280 specimens of chronic pancreatitis were examined to determine the type and frequency of epithelial dysplasia of the duct system. The epitheilal dysplasias were divided into 3 degrees of severity according to cytological and histological criteria. Dysplasia was demonstrable in 40.1% of the 280 specimens. Of these 32.9% were classified as dysplasia grade I and 7.1% as dysplasia grade II. Dysplasia grade III did not occur. The epithelial proliferations were correlated with the topography, the stage of the scarring and the degree of obstruction of pancreatic secretion. An increase in dysplasia was evident in relation to the stage of the scarring and to the obstruction of secretory outflow. In correlation with the topography of the chronic pancreatitis there was the highest frequency of epithelial dysplasias in uniformly scarred glands (47.7%). Papillary and pseudopapillary hyperplasias with atypia were demonstrated in 17.9 vs. 4.5% of the cases with epithelial proliferations.