Deletion of the long arm of chromosome 7 has been related to loss of tumor suppressor genes which may constitute a primary step of carcinogenesis in many kinds of malignancies, including low-grade B-cell lymphoma. However, deletion of the short arm of chromosome 7, del(7p), in low-grade B-cell lymphoma has not been reported. Here, we report a case of gastric MALT lymphoma with the chromosome aberration del(7p) which progressed in spite of eradication of Helicobactor pylori. Deletion 7p may represent a new karyotypic change that is possibly related to autonomous growth of MALT lymphoma.