Helicobacter pylori gastric infection in children is a public health problem. Classical diagnostic tools such as endoscopy are excessively invasive in the usual clinical context. Serology at this age has multiple drawbacks. The urea-13C breath test seems today the most appropriate alternative method. The principle of the test relies upon the indirect detection of H pylori through its high urease activity. The test uses a stable (ie, non radioactive) isotope, which allows its repeated use. The main indications are the detection and the follow-up of H pylori infection.