Nine cases of mantle cell lymphoma with gastrointestinal involvement were retrospectively reviewed, and their clinical features, including the involved organs, macroscopic forms, treatment methods, and prognoses were evaluated. The involved organs in the gastrointestinal tract were the stomach in 5 cases, the duodenum in 4, the ileum in 5, the cecum in 1, the colon in 4, and the rectum in 2. The macroscopic form of the gastric involvement varied, and included the protruding type in 3 cases, the ulcerated type in one, and the superficial type in one. On the other hand, the macroscopic form of the intestinal involvement from the duodenum to the rectum was mostly of the multiple lymphomatous polyposis type, which was observed in 6 cases. A hyper CVAD/MA regimen and high-dose chemotherapy with autologous peripheral blood stem cell transplantation was performed in 5 cases. All of these 5 cases continue to show a complete response.