Several techniques have been proposed to diagnose H. pylori infection based either on the direct or indirect detection of the bacteria. [table: see text] The current direct methods are performed on biopsy specimens obtained at endoscopy. Histological examination must always be performed because in addition to H. pylori detection it allows observation of the lesions present. Culture, while more demanding in terms of transport conditions, is a sensitive technique which is worthwhile when the patient might be treated with antibiotics to which the bacteria may be resistant. PCR has been more recently introduced and exhibits a good sensitivity and specificity. Rapid tests, such as the rapid urease test and examination of a Gram stained biopsy smear, are convenient and cheap but of lower sensitivity. Indirect methods are based either on the serological IgG response or the labelled urea breath test. Both are sensitive. The breath test is especially adapted to post-treatment control while serology is of interest for screening patients and epidemiological studies. New techniques have recently been proposed but are not yet applicable to routine diagnosis: detection of H. pylori in faeces by culture or PCR; detection of IgG antibodies in saliva or urine.