BACKGROUND: The purpose of this study is to compare validity of 5 diagnostic tests of helicobacter pylori with each other: stool antigen test, urea breath test (UBT), Rapid urease test (RUT), serology and histology.METHODS: A total of 94 patients who had indication of endoscopy entered the study. All of the 5 tests were performed for each patient. When the results of at least 2 tests were positive (except serology), Helicobacter pylori infection was considered to be positive. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under receiver operating characteristic (ROC) curve of these 5 tests were determined.RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under ROC curve of these 5 tests are as below, respectively. Histology: 89%, 78%, 93%, 91%, 85% and 0.881, RUT: 93%, 75%, 95%, 94%, 86% and 0.831, serology: 50%, 54%, 46%, 61%, 52% and 0.563, stool antigen test: 96%, 83%, 98%, 96%, 91% and 0.897, UBT: 89%, 73%, 92%, 90%, 82% and 0.892.CONCLUSIONS: Stool antigen test is the most accurate test for Helicobacter pylori diagnosis before eradication of these bacteria.