A large number of diagnostic tests are available for the diagnosis of Helicobacter pylori infection. These diagnostic methods include invasive and noninvasive methods. Culture yields the highest specificity and moreover allows the determination of strain resistance against antibiotics. Histology besides detection of H. pylori allows to assess morphological changes of the gastric mucosa. In clinical practice, the rapid urease test is very convenient and highly accurate. The 13C-urea breath test and the recently developed stool antigen test are reliable noninvasive tests with a high diagnostic accuracy in pre- and posttreatment conditions. Serological tests have a lower diagnostic accuracy and should only be used for screening of H. pylori infection or after careful local validation.