To investigate the prognostic value of histologic and clinical factors in lymphomas of the gastrointestinal (GI) tract, the clinicopathologic findings in 56 Japanese patients with GI lymphomas were reviewed. They included 37 patients with gastric and 19 with intestinal lymphomas. The male to female ratio was 2.7:1 in gastric and 11:1 in small intestinal lymphomas. Histologically, all but one of intestinal lymphomas were high-grade lymphomas. Gastric lymphomas comprised 47% of low-grade and 53% of high-grade tumors. Significant factors for favorable prognosis identified by Cox's multivariate analysis were female sex, the presence of reactive lymphoid hyperplasia (RLH) in the primary site, early stage of disease, gastric lymphomas, and low-grade histologic type. The important role of chronic lymphocytic infiltration for development of gastric lymphoma was suggested by the high incidence of RLH and the intermediate lymphocytic type of lymphoma.