The majority of gastric B-cell lymphomas histologically are classified as low grade mucosa-associated lymphoid tissue (MALT lymphoma) and diffuse large B-cell lymphomas (DLBCL). There is evidence that the different histologic types are genetically heterogeneous, evolving through different pathogenetic pathways. Recurrent cytogenetic aberrations have been found in MALT lymphoma, whereas in DLBCL, limited cytogenetic data are available. We report here a DLBCL and a Burkitt-like gastric lymphoma case, cytogenetically studied by G-banding and M-FISH technique. In the first case, gains of chromosome 3, 7, 13, and 18 were found. An additional ring chromosome 1 identified as a clonal abnormality suggested clonal evolution. In the second case, trisomy 8, del(6)(q13), as well as t(8;14), t(1;5), and t(1;7), were observed. To our knowledge, cytogenetic data for gastric Burkitt-like lymphoma have not been reported, and M-FISH has not previously been used in the study of gastric lymphomas.