en Infectious Diseases Infectious Diseases Original Article Original Article <span style="font-size:14px;"><span style="font-family:times new roman;"><span style="color:#0000FF;"><strong><em>Background</em></strong><em>:</em></span> Hepatitis B Surface antigen (HBsAg) seroclearance and seroconversion (development of antibodies against HBsAg) can increases the survival of Chronic hepatitis B (CHB) patients. The aim of this study was to determine the percentage and timing of HBsAg seroclearance and seroconversion in patients with chronic hepatitis B infection.<br> <span style="color:#0000FF;"><strong><em>Methods</em></strong><em>:</em></span> 1026 patients with CHB infection who referred to a private clinic were included. These patients had been followed-up for an average of 15 years. The patients whose HBs Ag was cleared from the blood and remained negative until the end of follow-up were designated as HBs Ag serocleared and the patients whose HBs Ab was positive during follow-upwas designated as HBs Ag seroconverted. The time of seroclearance and seroconversion of patients was recorded. Liver function tests, alpha-fetoprotein (AFP) and Hepatitis B early antigen (HBe Ag) status were extracted from the patients&rsquo; medical records. Data were analysis with SPSS 17.<br> <span style="color:#0000FF;"><strong><em>Results</em></strong><em>:</em></span> The duration of follow-up was from 2 to 410 months and most patients were males (58.2%).<br> The survival rate of HBs Ag positivity after 5, 10 and 15 years were 95.6, 89.4 and 80.7%, and 98, 93.5 and 84.9% of patients had not yet developed anti-HBs antibodies after 5, 10 and 15 years, respectively. Age, gender and taking medication had no effect on HBs Ag clearance from the blood or anti-HBs production<br> <span style="color:#0000FF;"><strong><em>Conclusion</em></strong><em>:</em> </span>The HBs Ag seroconversion is a rare occurrence, but the incidence of this may increase with time, age and drug consumption. Though there was no relationship in our patients</span></span><br> &nbsp; Chronic Hepatitis B, Seroclearance, Seroconversion, Hepatitis B Surface antigen 205 210 http://caspjim.com/browse.php?a_code=A-10-125-10&slc_lang=en&sid=1 jila Masrour-Roudsari masrour_j@yahoo.com 100319475328460027836 100319475328460027836 No Student Research Committee, Babol University of Medical Sciences, Babol, Iran Mohammadreza Hasanjani-Roushan hagar2q@gmail.com 100319475328460027837 100319475328460027837 No Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, I.R. Iran. Yousef Yahyapour uyahyapoor@yahoo.com 100319475328460027838 100319475328460027838 Yes Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Rahim Barari-Savadkoohi savadkouhi330@yahoo.com 100319475328460027839 100319475328460027839 No Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Ali Bijani alibijani@yahoo.com 100319475328460027840 100319475328460027840 No Social Determinants Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Farzin Sadeghi sadeghifarzin6@gmail.com 100319475328460027841 100319475328460027841 No Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Mousa Mohammadnia-Afroozi mousamohammadnia@yahoo.com 100319475328460027842 100319475328460027842 No Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, I.R. Iran.