We report a case of intermediate lymphocytic lymphoma (ILL) with multiple lymphomatous polyposis. A 56-year-old man presented with general fatigue and bloody stool. Physical examination showed cervical and axillary lymphadenopathy, bilateral tonsillar hypertrophy, and moderate splenomegaly. Leukocyte count was 9,570/microliters with 11% abnormal cells, infiltration of which was observed in the bone marrow too. Examinations of the gastrointestinal tract revealed diffuse small polypoid lesions throughout the stomach and the entire large bowel. The biopsied specimens from both the stomach and large bowel showed diffuse infiltration of medium-sized lymphoid cells in the submucosa and the lamina propria. Lymph node biopsies showed ILL (mantle zone lymphoma). The phenotype of lymphoma cells was CD5 (+) CD10 (-) CD19 (+) CD20 (+) CD21 (+), and sIg mu delta-lambda. The patient was initially given the multiple agent chemotherapy, which did not improve the peripheral blood findings and was switched to the regimen that comprised of etoposide and prednisolone. The patient's lymphoma is well controlled by this regimen 35 months after diagnosis.