The classification of tumors is important for understanding tumor histogenesis, for predicting prognosis, for differential diagnosis, and for recommending appropriate therapy. Since 1836, when pancreatic cancer was first described, progress has been made in pancreatic cancer morphology, and a number of classifications have been proposed. All of these classifications are mainly based on morphological characteristics. Some are too detailed to be of practical use while others are more pragmatic. Some of the inherent problems in the previous classifications included difficulties in obtaining an adequate number of pan­ creatic tumors for examination and insufficient clinical data and follow-up. With the increasing incidence of pancreatic cancer in many parts of the world during the past six decades, and with the availability of more tumors to patho­ logists, advances have been made in pancreatic tumor studies. Classifications by Cubilla and Fitzgerald and by Kloppel, which are generally similar, mostly considered prominent morphological features and their histogenesis. These pathology-oriented classifications, although complete, were not practical from the standpoint of clinicians concerned with the prognosis of individual tumors.