Abstract:Abstract: Objective To investigate the relationships between Helicobacter pylori infection and inflammatory bowel diseases. Methods From January 2003 to December 2015, 165 patients diagnosed as ulcerative colitis (UC) or Crohn's disease (CD) were enrolled in the First Affiliated Hospital of Dalian Medical University, 165 hospitalized patients of chronic gastritis during the same period were enrolled as controls. All the patients received rapid urea test by endoscopy to detect Helicobacter pylori infection. The Helicobacter pylori infection rates of these two groups were analyzed statistically. Results There were 149 cases of UC patients (70 male cases) and 16 patients with CD (9 male cases). There were significant differences in Helicobacter pylori infection rates between the control group and both the UC and CD groups (P < 0.05). And the Helicobacter pylori infection rate of the CD patients was lower than that of the UC patients (P < 0.05). Moreover, the Helicobacter pylori infection rate in the E1 group (lesions in the rectum) and the E2 group (lesions in the left colon) had no significant difference (P > 0.05). But the Helicobacter pylori infection rate in the E3 group (lesions in extensive or complete colon) was lower than those in the E1 and E2 groups (P < 0.05). Conclusions Helicobacter pylori infection rates in the patients with inflammatory bowel diseases are lower than that in the patients with chronic gastritis, but still at a high level. Helicobacter pylori infection rate in the patients with CD is lower than that in the patients with UC. Helicobacter pylori infection rate in the UC patients with pan-colon involvement is lower than that in the UC patients with rectum or left colon involvement. Helicobacter pyloriinfection may be a protective factor in the patients with inflammatory bowel diseases.