Abstract: AIM: To observe the relationship between Helicobacter pylori (Hp) infection and unstable angina pectoris (UAP). METHODS: One hundred and fifty-two patients with angina pectoris from Tianjin Medical University Hospital were divided into UAP group (n=114) and stable angina pectoris group (SAP, n=38). The concentration of the Ig-G antibodies to Hp (Hp-IgG) was determined by enzyme-linked immunosorbent assay (ELISA). The concentration of the high-sensitivity C-reactive protein (hsCRP), total cholesterol (TC), triglyeride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were determined. Coronary angiography was performed in all patients to assess the degree of coronary artery stenoses. RESULTS: Levels of serum Hp-IgG, hsCRP and FPG were higher in UAP group than in control group. Multivariate logistic regression analysis showed that the higher levels of Hp-IgG (OR=5.13, 95%CI 1.91-13.78, P<0.01), hsCRP (OR=3.58, 95%CI 1.32-9.65, P<0.05) and FPG (OR=6.20, 95%CI 1.21-31.42, P<0.05) were risk factors for UAP patients. CONCLUSION: The concentration of serum Hp-IgG is higher in UAP patients. The higher level of Hp-IgG is significantly associated with UAP.