Helicobacter pylori is one of the most common causes of chronic bacterial infection in humans, and it is associated with many diseases of the upper gastrointestinal tract. The 13C urea breath test (13C-UBT) is a simple, non-invasive and global test for Helicobacter pylori detection. The test reflects the hydrolysis of 13C-labelled urea by Helicobacter pylori urease. The 13C-UBT is the gold standard test for Helicobacter pylori infection. Since the original description (in 1987) several modifications of 13C-UBT have been published to simplify and optimise the test. However, neither Standardised European Protocol nor Standard US Protocol were accepted. This paper gives the methodology of the 13C-UBT based on eur own study and on the review of the literature.