Elbasvir/grazoprevir (EBR/GZR) is a new generation, fixed-dose, combination antiviral drug used in chronic hepatitis C virus (HCV) genotype (GT) 1 or 4 infection. Our study evaluates the clinical efficacy and safety of EBR/GZR after its launch in Taiwan. This is a retrospective observational study. Patients who had received EBR/GZR for chronic HCV GT 1 between June 2017 and April 2018 were recruited. Patients' age, sex, HCV GT, changes in HCV RNA level before and after treatment, sustained virologic response 12 weeks (SVR12) after the cessation of drug administration, side effects, and interaction effects were used to evaluate the clinical efficacy and safety. A total of 149 patients were recruited. Of them, 145 (97.3%) had HCV GT 1b, and the rest had HCV GT 1a; most of the EBR/GZR-related side effects in this study were mild. Three participants were discontinued because their alanine transaminase levels were elevated to over 10 times the upper limit of normal. The therapeutic effect analyses revealed a rapid virologic response rate of 95.3% and an SVR12 rate of 98%. Subgroup analyses performed using SVR12 as the outcome variable revealed three demographic factors HCV GT 1, hepatocellular carcinoma medical history, and noncirrhosis plus HCV RNA level. This study confirmed that EBR/GZR is safe and effective for treating patients with HCV GT 1 and exhibited excellent overall clinical efficacy in Taiwan. The therapeutic effects are unrelated to factors such as sex, HCV RNA level before treatment, and history of liver cirrhosis. © 2019 The Authors. Journal of Medical Virology Published by Wiley Periodicals, Inc.