Plasmablastic lymphoma (PBL) has initially been described as a rapidly progressive and almost invariably fatal diffuse large-cell lymphoma with plasmablastic features, exclusively involving the jaw and oral mucosa in HIV-positive patients. Although its clinical features may help in differential diagnosis, an extra-oral localization in a patient without HIV makes it more difficult to suspect clinically. We describe a very rare case of gastric PBL primarily involving stomach in a middle age man without an HIV infection. A biopsy was performed and its findings revealed a diffuse, monomorphous proliferation of the tumor cells with features of immunoblasts, MUM-1, EMA, and lambda light chains positive. Serology was negative for the human immunodeficiency virus (HIV), HBsAg, and hepatitis C virus infection. The patient started treatment with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy, but unfortunately died before the second cycle was given. To our knowledge, this is the second case of gastric PBL presented in HIV-negative patients. The findings in this case suggest that PBL should be included in the differential diagnosis of gastrointestinal tumors.