Multiple lymphomatous polyposis (MLP) is an uncommon type of primary non-Hodgkin's gastrointestinal B-cell lymphoma characterized by the presence of multiple lymphomatous polyps along the gut. We present a patient with MLP in which the involvement was unusually widespread. The diagnosis was confirmed by the typical polyposis lesion, histology, phenotyping and clinical presentations. A 68-year-old man had a large mass at the ileocecal valve as well as multiple polyps along the whole digestive tract. At the time of diagnosis, lymphoma had involved bone marrow, peripheral blood, spleen, prostate and peripheral lymph nodes. The patient received 8 courses of chemotherapy with no remission. He died of pneumonia 11 months after diagnosis. Clinically, the diagnosis may be confused with epithelial polyps; and histologically, the diagnosis must be distinguished from benign lymphoid proliferations as well as other types of lymphoma. The prognosis for patients with MLP is relatively poor (the median survival is usually less than 3 years).