['The molecular mechanism between Helicobacter pylori (H. pylori) infection and gastric cancer remained largely unknown. In this study, we determined the role of miRNA in H. pylori induced gastric cancer.', 'We found that miR-204 was decreased in H. pylori positive tissues by qRT-PCR. Knockdown of miR-204 enhanced the invasion and proliferation ability of gastric cancer cells in vitro. Luciferase assay revealed that SOX4 was target gene of miR-204, which was found up-regulated in H. pylori positive tissues. Down-regulation of miR-204 and over-expression of SOX4 promoted epithelial-mesenchymal transition process.'] Does decreased miR-204 in H. pylori-associated gastric cancer promote cancer cell proliferation and invasion by targeting SOX4?