A 57-year-old male with right ocular adnexal mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) was successfully treated with local radiation therapy. The gastroendoscopic examination revealed a slight inflammatory change of the gastric mucosa, and the urease test was positive. Eradication therapy against Helicobacter pylori was successfully done, however, the patient developed gastric MALT lymphoma two years after the initial treatment. Southern blot analysis of the immunoglobulin heavy chain gene rearrangement revealed that the lymphoma cells from the ocular adnexal and gastric MALT lymphomas were identical, indicating that the gastric MALT lymphoma was not the primary but the metastatic region from the ocular adnexal MALT lymphoma. Further, immunohistochemical staining demonstrated the expression of integrin alpha4beta 7 on ocular adnexal MALT lymphoma cells, which is essential for the adhesion of lymphocytes to gastrointestinal mucosa. These results indicate that ocular adnexal MALT lymphoma cells can metastasize to the stomach, depending on the adhesional function of integrin alpha4 beta7.