A 54-year-old male was referred to our hospital because of diarrhea and easy fatigabity. Barium meal examination of upper GI tract and the small intestine revealed innumerable polypoid lesions extending from the stomach to the ileum. Barium enema study revealed innumerable polypoid lesions in the cecum, ascending colon, sigmoid colon, and the rectum. Biopsied specimens taken from the stomach and a polypectomized specimen taken from the ascending colon were diagnosed as MLP. Histologically and clinically we could not diagnose this case as malignant lymphoma. Therefore, we observed without any treatment. Five and nine months later, reexamination were performed. The X-ray and endoscopic findings showed a decrease in number of polyps of the colon. In this case, improvement of MLP was observed without any treat-ment, so it seems difficult to make a definite diagnosis of benign or malignant characteris-tics at present.