Helicobacter pylori (H. pylori) induces hyperproliferation of the gastric mucosa. This study was designed to clarify whether H. pylori infection is involved in the gene expression of hepatocyte growth factor (HGF), a potent stimulator of cell proliferation in gastric mucosa. Levels of HGF mRNA were determined by a reverse transcription-polymerase chain reaction in endoscopic gastric biopsy specimens from 9 control subjects and 9 patients with H. pylori infection. In patients with H. pylori infection, levels of HGF mRNA in gastric mucosa were significantly higher than those in control subjects. HGF mRNA levels in patients with H. pylori infection were correlated with the severity of gastric mucosal inflammation. Our observations indicate that H. pylori infection increases the expression of HGF gene in gastric mucosa probably through the mucosal inflammation.