Embryologically the pancreas head consists of a dorsal and a ventral portion and these were able to be differentiated by the shape of the islets and the density of pancreatic polypeptide (pp) cells. We examined histologically the modes of spread of carcinoma of the head of the pancreas. The material were 15 cases with T1 and T2 cancer resected (T1;8;T2;7) and included 8 tumors arising from a ventral pancreas and 7 dorsal. We conclude that most of pancreas head cancers arising from a ventral pancreas involved the retropancreatic soft tissue at the early stage, and those arising from a dorsal pancreas showed an apparent tendency of a spread to the epithelial linings of the main pancreatic duct.