en Virology Virology Original Research: Clinical Science Original Research: Clinical Science <strong>Background: </strong>Hepatitis C virus (HCV) infection is a cause of major liver complications, particularly in patients infected with human immunodeficiency virus (HIV). This study aimed to evaluate the efficacy of pegylated interferon (Peg-IFN) and a fixed dose of ribavirin treatment among Iranian HCV mono-infected and HCV/HIV-co-infected patients.<br> &nbsp;&nbsp; <strong>Methods: </strong>A total of 214 HCV mono-infected and HCV/HIV co-infected patients attending Liver Disease Center in Tehran were assigned to receive treatment with Peg-IFN-&alpha;2a or -&alpha;2b plus ribavirin for 24-48 weeks. Sustained virologic response (SVR) was used as the primary efficacy endpoint of Peg-IFN and ribavirin therapy.<br> &nbsp;&nbsp; <strong>Results:</strong> Treatment with Peg-IFN and ribavirin has been associated with a considerably higher rate of SVR (24 weeks for HCV genotype 3 and 48 weeks for HCV/HIV co-infected and HCV genotype 1 patients). Overall, the clearance of HCV-RNA at the end of therapy occurred in 48.6% of patients. Adverse events leading to treatment discontinuation were seen in 14% of patients.<br> <strong>&nbsp;&nbsp; Conclusion:</strong> This retrospective study revealed a relatively well-tolerated response in both HCV mono-infected and HCV/HIV co-infected patients during treatment with Peg-IFN and ribavirin. However, the recent revolutionized interferon-free therapies for chronic HCV infection should be taken into account for achieving a greater response and minimal adverse events. Hepatitis C, HIV, Pegylated interferon, Ribavirin, Iran 380 385 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-2447-6&slc_lang=en&sid=1 Khashayar Hesamizadeh kh.hesamizadeh@gmail.com 200319475328460062608 200319475328460062608 No Middle East Liver Disease (MELD) Center, Tehran, Iran Ahmad Tavakoli ahmad.tavakoli66@gmail.com 200319475328460062609 200319475328460062609 No Department of Medical Virology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran Mehri Nikbin nikbin_mehri@yahoo.com 200319475328460062610 200319475328460062610 Yes Middle East Liver Disease (MELD) Center, & Baqiyatallah Research Center for Gastroenterology and Liver Diseases (BRCGL), Baqiyatallah University of Medical Sciences, Tehran, Iran