BACKGROUNDS: Helicobacter pylori infection is now recognized as a cause of chronic gastritis, peptic ulcer disease, gastric carcinoma and lymphoma. Several diagnostic methods of H. pylori infection, such as histopathology, culture, rapid urease test, urea breath test, serologic test and polymerase chain reaction(PCR) have been used. This study aimed to compared with different diagnostic methods of H. pylori infection and determined the appropriate cut-off value of IgG anti-H. pylori antibody using receiver operating characteristic(ROC) curve. METHODS: We compared sensitivities, specificities and efficiencies of histology, CLO test, culture, IgG anti-H. pylori Ab and PCR using the ureC gene in gastric biopsy specimens from 112 H. pylori patients and 140 control group. RESULTS: The sensitivities of histology, CLO test, culture, IgG anti-H. pylori Ab and PCR were 72%, 91%, 86%, 82% and 94%, respectively and the specificities of histology, CLO test, culture, IgG anti-H. pylori Ab and PCR were 96%, 99%, 100%, 73% and 99%, respectively. The efficiencies of histology, CLO test, culture, IgG anti-H. pylori Ab and PCR were 88%, 96%, 89%, 77% and 97%, respectively. From the ROC curve, the cut-off value of the anti-H. pylori Ab determined 10U/mL in which sensitivity was 82% and specificity was 82%. CONCLUSIONS: These findings suggest that the PCR assay in gastric biopsy is the most sensitive and efficient diagnostic method of H. pylori infection and the cut-off value of the anti-H. pylori Ab determines 10U/mL showing highest efficiency.