In order to find a relationship between ductal hyperplasia and carcinoma of the pancreas, histological and histochemical examinations were made on pancreatic specimens of 1,174 autopsy patients with special attention to the age incidence of the former. Ductal hyperplasia was divided into 3 types; nonpapillary, papillary, and atypical hyperplasia. All three types of hyperplasia and ductal carcinoma showed a similar tinctorial property in mucous histochemistry. In general, atypical hyperplasia was seen in the pancreas having papillary hyperplasia which was found in the pancreas associated with nonpapillary hyperplasia. All three types of hyperplasia were apparently more frequent in cancerous pancreases than in non-cancerous ones. They were also more common in the head of the pancreas than in the body and tail. Age incidence also suggests a sequential change from nonpapillary hyperplasia through papillary and atypical ones to carcinoma.