Purpose: Infection with Helicobacter pylori is an important risk factor for gastric cancer in humans. We compared the clinicopathologic features of gastric cancer patients based on H. pylori infection. Materials and Methods: We prospectively studied 155 patients who had gastric cancer and underwent gastrectomies in 1 hospital in Korea. We examined H. pylori infections using the rapid urease test (RUT) with gastrectomy specimens and collected clinical and pathologic data. Results: The number of H. pylori infections based on the RUT was 137 (88%). The H. pylori-negative group was significantly associated with AGC and tumor histology. H. pylori infection was significantly correlated with type I/IIa in EGC and type III/IV/V in AGC. AGC was significantly correlated with larger tumor size, lymphatic invasion, perineural invasion, and H. pylori infection based on univariate and multivariate analyses. Conclusions: We report the prevalence of H. pylori based on the RUT in gastric cancer patients. H. pylori infection influences the tumor histology, progression, and growth type of gastric cancer.