Lymphomas presented in any organ or tissue other than lymph nodes or the spleen are considered primary extranodal non-Hodgkin's lymphomas, and the most common non-Hodgkin's lymphomas are of the gastrointestinal tract. The most common histological subtypes are marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue and diffuse large B-cell lymphoma, and typically only one to two organs are affected. Patients present with a wide variety of vague complaints, making early diagnosis problematic. Herein, we report the case of a 76-year-old male with extranodal marginal zone B-cell lymphoma involving the entire gastrointestinal tract, sparing only the esophagus, who was Helicobacter pylori-negative. He underwent six courses of chemotherapy with R-CHOP regimen, and achieved complete remission.