Recently the Japanese Society for Helicobacter Research (JSHR) published the guideline for the diagnosis and treat- ment of H. pylori infection. 2 It is estimated that the Japanese Ministry of Health and Welfare will approve the diagnosis and treatment of H. pylori infection as the health insurance- covered medical services in the near future. The aim of this paper is to review current endoscopy-based diagnostic modalities for H. pylori infection and to emphasize their preferential indications, taking into account the particular settings in which a diagnosis is to be made. BIOPSY SITE, NUMBER AND BIOPSY FORCEPS It is now well-recognized that persistent H. pylori infection develops atrophic gastritis leading to intestinal metaplasia. Intestinal metaplasia and patchy distribution of the bacteria are thought to be factors causing false-negative diagnoses of H. pylori infection. There are several reports regarding biopsy sites and number for the accurate diagnosis of H. pylori infection. Hazzel et al. reported that it was necessary to take biopsies from both the antrum and the body, as H. pylori might be found in either of them. 5 Genta and Graham reported that two antral biopsy specimens, one from lesser cur- vature and one from greater curvature, yield virtually 100% sensitivity for the histological detection of H. pylori in- fection. They also recommended three biopsy specimens (one from each of lesser curvature and greater curvature of the antrum and greater curvature of the corpus) as a rou- tine evaluation of H. pylori infection, because no patients having extensive atrophic gastritis with intestinal metaplasia were included in their series. 3 Satoh et al. indicated that the INTRODUCTION The wide recognition that Helicobacter pylori plays an essential role as a causative agent in several gastroduodenal diseases has made the diagnosis of H. pylori infection indis- pensable in many different circumstances. Numerous inva- sive and non-invasive diagnostic tests have been developed since the original description of H. pylori by Marshall and Warren in 1982. 1 The invasive biopsy-based tests that include rapid urease test, histology and culture are impor- tant generally in the assessment of H. pylori status before eradication. Initial endoscopy allows assessment of treat- ment indications of H. pylori infection such as peptic ulcer disease and mucosa-associated lymphoid tissue lymphoma (MALToma). 2 In view of the irregular distribution of H. pylori, all the biopsy-based tests may theoretically cause a false-negative result. The inherent risk of sampling error can, however, be virtually eliminated by obtaining several biopsy samples from not only the gastric antrum but also the gastric corpus. 3,4 In contrast to biopsy-based methods, non- invasive tests assess the global presence of H. pylori in the stomach, even when the bacteria are irregularly distributed on the gastric mucosa. Non-endoscopy-based tests are cheaper, more convenient and thus should be preferred in the situations where the exclusive information obtained by endoscopy is not needed. Digestive Endoscopy (2001) 13, 3–6 REVIEW ARTICLE RECENT PROGRESS IN ENDOSCOPY-BASED DIAGNOSIS OF HELICOBACTER PYLORI INFECTION Tadashi Sato, Masayuki A Fujino, Fumiaki Kitahara and Murdani Abdullah First Department of Medicine, Yamanashi Medical University, Yamanashi, Japan Numerous invasive and non-invasive tests are available in the detection of Helicobacter pylori. Endoscopy-based tests that include rapid urease test, histological examination and culture are important generally in the assessment of H. pylori status before eradication therapy. Recently, several new endoscopy-based diagnostic methods have been developed aiming at rapid and accurate detection of the organisms. It would be possible to diagnose H. pylori infection in treated patients by using these new highly sensitive tests. Although the diagnosis of H. pylori infection itself is possible by using non-invasive diagnostic tests, endoscopy-based tests provide not only the diagnosis of the organisms, but also the exclusive information such as treat- ment indications and the susceptibility for the antimicrobial drugs. Recently, new triple therapy including clarithromycin has been widely performed in Japan. Along with an increase in the prevalence of the antibiotic-resistant strains, culture may become a more important diagnostic method in the future. The inappropriate application of the tests may increase the potential risk of the misdiagnosis and the treatment failures. The diagnostic method should be selected by taking into account the circumstances in which a diagnosis is to be performed. Key words: endoscopy-based diagnosis, Helicobacter pylori. Correspondence: Tadashi Sato, First Department of Medicine, Yamanashi Medical University, 1110 Shimokato, Tamaho-cho, Nakakoma-gun, Yamanashi, 409-3898, Japan. Email: tadashis@res.yamanashi-med.ac.jp Received 5 October 2000; accepted for publication 10 October 2000.