Introduction. More than half of the adult global population are carriers of H.pylori, a Gramnegative microaerobic human pathogen, which is associated with various gastroduodenal diseases. Diagnostic tests are divided into noninvasive (UBT, SAT, serology) and invasive methods (culture, histology, PCR, RUT). Using the appropriate test is important to avoid diagnostic error. Aim of the study. The aim of this paper was to review the application principles of H. pylori diagnostic methods in practice. Materials and methods. A systematic literature search for both original researches and review articles in biomedical databases was made through Google scholar, PubMed and Medline. Results. UBT is useful to confirm eradication and screening, no sampling errors, useful for children with false negative result in case PP, antibiotics intake, gastric pathologies and false positive in case of urease positive bacteria growth, also it doesn't provide data about bacterial resistance. SAT is preferred in children rather than serological and UBT which may be equivocal or difficult to perform with false positive in case of contamination or cross reaction with other species. It is affected by the stool quality without data about resistance. Serological test is the cheapest without false negative result except in early infection, which is recommended for screening because it is not influenced by GIT pathologies and drugs but without data about resistance and differentiation between active and past infection. RUT need at least 10000 organism to obtain a positive result with false negative result due to PPI and achlohydria and false positive result due to other urease positive bacteria. PCR provide data about antibiotic resistance, its limitations are the cost, equipment, time, skilled staff. Culture provide data about antibiotic resistance but it is the most expensive method and timeconsuming. Histological examination limitation is due to the dependence on the operator skill, interobsever variability, site, size, number of biopsy taken and staining method type. Conclusions. The choice of diagnostic tests to determine H. pylori infection status depends on the sensitivity, specificity, availability, cost, and rapidity of the results, laboratories level ,the patients clinical status. Unfortunately, none of the currently used methods are able to fulfill this criteria. One solution is to combine the results of two or more techniques, and compare with results of each method being evaluated.