Helicobacter pylori provides the pathogenic background for the development of gastric MALT-type lymphoma. The assessment of H. pylori is limited by the accuracy of the detection method used. Especially in patients with low-grade MALT-type lymphoma, the H. pylori status is the crucial question for therapeutic management. In this study, 60 patients with gastric MALT-type lymphoma. (lowgrade, 22; high-grade, 38) were investigated for the presence of H. pylori by histologic and serologic means. In 98% of the patients with MALT-type lymphoma, H. pylori-specific IgG serum antibodies were detected. In contrast, on histologic examination, H. pylori was found only in 78% of the patients (low-grade, 77%; high-grade, 79%). In this study, a discrepancy between serologic and histologic evaluation of the H. pylori status in gastric MALT-type lymphoma was found. Therefore, a H. pylori eradication therapy in low-grade MALT-type lymphoma, which often leads to a complete tumor regression, should not be excluded as a first line therapy because of a negative H. pylori status on histologic examination.