Mantle cell lymphoma represents 2.5-7% all of non Hodgkin's lymphomas. Stomach is the most common site of extranodal lymphoma. However, that is not the case with mantle cell lymphoma, which is extremely rare. We present a case of 71-year-old woman admitted to the Internal Clinic of the University Clinical Hospital Center Rijeka, because of stomach discomfort and melena. Endoscopy and computed tomography revealed a polyp in gastric antrum. Histopathologic, immunohistochemic and genetic methods were also performed and the results were consistent with primary gastric mantle cell lymphoma without periepigastric and/or local or distant abdominal lymph node involvement.