Abstract: AIM:To investigate the relationship between Helicobacter pylori(Hp) infection and coronary artery disease(CAD).METHODS:There were 263 cases divided into two groups.There were 88 cases in the normal group and 175 cases in the CAD group.Patients in the CAD group had >50% coronary stenosis diagnosed by coronary angiography.Those patients with a history of previous Hp eradication and/or malignancy were ruled out.The tissue was acquired by gastroduodenoscopic biopsy and then stained by Warthin-starry silver stain.RESULTS:There were significant differences between groups in gender,age,smoking habit and high-density lipoprotein cholesterol(HDL-C).There was no statistical difference in Hp infection ratio between groups(32% vs.42%).Six months later,82 patients of the CAD group who had been treated by percutaneous coronary intervention(PCI) experienced angiography once again.Twenty-one(36%) of the 59 patients of the Hp-negative group and 12(52%) of the 23 patients of the Hp-positive group experienced new coronary stenotic lesion and in-stent restenosis.There was no statistical significance.CONCLUSION:There was no definite relationship between Hp infection and CAD.Further studies are needed in this area.