Since and intestinal polyposis in association with mucocutaneous pigmentations was first observed by Peutz in 1921 and ten subsequent cases were added by Jeghers(1949), numerous cases have been cumulated under the designation of Peutz- Jeghers syndrome. Substantial portions of these causes were once described as having polyps with malignant changes microscopically shown in such cases, extraintestinal metastatic lesions occurred very rarely, and even some malignant cases with metastasis did not provide the solid evidence of carcinomas originating from the Peutz-Jeghers polyps. Thus, it is our purpose to present a case of Peutz-Jeghers polyposis manifested with peculial hitology of pseudocarcinomatous glandular and mucinous trapping and to discuss its nature with special emphasis on the differential diagnosis from the genuine malignant change of this polyp.