Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 52 8 2014 08 15 582 590 EN Payam Dindoost Department of Gastroenterology, Middle East Liver Diseases Center (MELD Centers), Tehran, Iran. Narges Chimeh Department of Psychiatry, Family Research Institute, Shahid Beheshti University, Tehran, Iran. Blain F Hollinger Department of Gastroenterology, Baylor College of Medicine One Baylor Plaza, Houston, USA. Esmaeil Saberfar Department of Virology, Bayerpaul (BP) Vaccines and Pharmaceutical Company, Tehran, Iran. Mehdi Norouzi Department of Virology, Faculty of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Seyed Mohammad Jazayeri Department of Virology, Faculty of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 11 Occult hepatitis B (OHB), or persistent hepatitis B virus (HBV) viremia in surface-antigen-HBsAg-negative patients, has been recognized as a medical concern during the last decade. The exact magnitude, pathogenesis and clinical relevance of OHB are unclear. This review organizes the published data on OHB and presents an overview of the current hypotheses on OHB's pathogenesis and clinical relevance.Many explanations have been offered for the pathogenesis of OHB, ranging from the inability of standard immunoassays to diagnose OHB to the involvement of the versatile virus-host factors. Also, special care should be taken regarding the diagnosis of OBH. It seems that both shared viral-host factors are involved in the pathogenesis of OBH. Further molecular studies on cohort patients group need to explore such association. https://acta.tums.ac.ir/index.php/acta/article/view/4570 https://acta.tums.ac.ir/index.php/acta/article/download/4570/4262