This observation reports that a hepatitis B virus (HBV) reactivation, as the result of hepatitis C virus (HCV) eradication on a dominant HCV coinfected HBV/HCV patient, was subsequently prevented by treating both viral infections together. This finding raises the question as to whether preemptive HBV treatment should be prescribed along with HCV treatment to prevent HBV from being reactive after HCV eradication in coinfected HBV/HCV patients.