As most pancreatic ductal carcinomas have the genotype of ductal epithelial cells it is believed that they originate from the epithelium of these structures. It has been proved that endocrine cells are frequently present in ductal carcinoma. Morphological, immunohistochemical, ultrastructural evaluation and statistical analysis revealed the presence of one or a few types of endocrine cells in 46.9% of ductal carcinomas (mainly of I degree or II degree malignancy). These cells were found to secrete insulin. Intermediate cells were not observed in ductal carcinoma. The structure of chronic pancreatitis, mainly the so called tubular complexes, showed various types of endocrine cells and numerous intermediate cells, often with features of destruction. The present study seems to prove that pancreatic cells have a common origin-acinar cells as well as islet cells arise from ductular cells. The intermediate cells observed in chronic pancreatitis are not just a transitory form in the differentiation of precursor cells, but rather the abnormal forms of cells that are produced in that process.