Objective To investigate the difference of clinical features between primary colorectal malignant T cell lymphoma and primary colorectal malignant B cell lymphoma.Methods Forty cases diagnosed as primary eolorectal malignant lymphoma (PCML) between Jan 1999 and May 2008 were studied retrospectively.Results The average age of 40 patients with PCML was (41.0±11.2) years old.Twenty-seven cases (67.5%) were diagnosed as B-cell lymphoma.Thirteen cases (32.5%) were diagnosed as T-cell lymphoma.Patients with T-cell lymphoma in PCML had more symptoms such as fever,night sweat and hematochezia,and was easier to perforate than those with B-cell lymphoma.Protrude type and single-focus and right-colon type were common in B-cell lymphoma under colonoscopy,but ulcerative type and multi-focus and fulbcolon were common in T-cell lymphoma.B-cell lymphoma had an earlier diagnosis,and more opportunities for surgery than T-cell lymphoma.Conclusions The misdiagnostic rate for PCML was high.Protrude type and single-focus and right-colon type were common in B-cell lymphoma under eolonoscopy,but ulcerative type and multi-focus and full-colon were common in T-cell lymphoma.B-cell lymphoma could be diagnosed earlier.