BACKGROUND/AIMS: It was reported that the prevalence of Helicobacter pylori (H. pylori) infection decreased after gastrectomy, but persistent H. pylori infection may cause residual gastritis or stump cancer. We studied the prevalence of H. pylori infection in patients who had undergone subtotal gastrectomy for the treatment of gastric cancer and the factors that influence H. pylori positivity in the remnant stomach. METHODS: Ninety-eight patients who had undergone radical subtotal gastrectomy (RSG group) for the treatment of gastric cancer and eighty-four patients diagnosed as having gastric cancer (GC group) were enrolled. H. pylori status was diagnosed by rapid urease test, histological examination, and 13C-urea breath test. We evaluated whether there were differences in various clinical characteristics according to the H. pylori status in the remnant stomach. RESULTS: The prevalences of H. pylori infection in RSG group and GC group were 55% and 69%, respectively. In RSG group, the prevalence of H. pylori was 76.9% in patients aged 49 or less, and it decreased with age. The prevalence of H. pylori within 3 years of gastrectomy was 59.5% and it decreased to 28.6% after 3 years of gastrectomy. CONCLUSIONS: The positive rate of H. pylori in RSG group is lower than that in GC group and decreases with age and time interval after operation.