Clinical manifestations and imaging findings of mantle cell lymphoma involving gastrointestinal tract were evaluated. The subjects were 7 cases of mantle cell lymphoma involving the gastrointestinal tract. All cases were pathologically confirmed in our hospital during the period from April 1994 to July 2000. Five patients were male and 2 were female, and their age ranged from 49 to 63 years (average 57.4). The objectives were: 1) characteristics and distribution of multiple polyposis, 2) presence, location and enhancement pattern of bowel wall thickening or mass formation, 3) presence of splenomegaly, 4) presence and location of abdominal lymph node enlargement, 5) involved extra-abdominal organs, 6) combined cancer and location, and 7) other findings. All mantle cell lymphomas occurred in elderly persons, over 40 years, and most showed multiple polyposis (6/7), bowel wall thickening or mass formation (6/7), lymph node enlargements (6/7) and extra- abdominal involvement (5/7). All cases of polyposis involved the small bowel and colon, and the size of the polyps ranged from 0.1-4.0cm. Four of 6 patients showed combined sessile and polypoid polyps, while the other 2 showed only sessile polyps. Most of or some of the polyps in 3 patients showed small central ulcerations. Most of the patients (5/6) showed an uncountable number of polyps. Polyposis was predominant in the rectum, ascending colon, rather than other sections in the colon, and the ileum were almost always involved by polyposis. Bowel wall thickening or mass formation developed exclusively in the ascending colon, rectum or ileum. Extra- abdominal involvement developed either simultaneously or nonconcurrently with gastrointestinal involvement. Some of patients showed splenomegaly (3/7), appendiceal enlargement (2/7), and intussusception (1/7), and some had associated adenocarcinomas (3/7).