This article presents the results of two phase 3 studies evaluating the efficacy and safety of sofosbuvir, a nucleotide polymerase inhibitor, in previously untreated patients with chronic hepatitis C virus (HCV) infection. The first study was a single-group, open-label trial involving 327 patients with HCV genotypes 1, 4, 5, or 6, while the second study was a randomized, open-label, active-control trial involving 499 patients with HCV genotypes 2 or 3. The primary endpoint was a sustained virologic response at 12 weeks after the end of therapy. In the single-group study, a sustained virologic response was achieved in 90% of patients. In the noninferiority trial, a sustained response was reported in 67% of patients in both the sofosbuvir-ribavirin group and the peginterferon-ribavirin group. Adverse events were less common with sofosbuvir compared to peginterferon. The study concluded that sofosbuvir combined with peginterferon-ribavirin achieved high efficacy and safety in previously untreated patients with HCV infection, particularly those with genotypes 1 or 4.This article presents the results of two phase 3 studies evaluating the efficacy and safety of sofosbuvir, a nucleotide polymerase inhibitor, in previously untreated patients with chronic hepatitis C virus (HCV) infection. The first study was a single-group, open-label trial involving 327 patients with HCV genotypes 1, 4, 5, or 6, while the second study was a randomized, open-label, active-control trial involving 499 patients with HCV genotypes 2 or 3. The primary endpoint was a sustained virologic response at 12 weeks after the end of therapy. In the single-group study, a sustained virologic response was achieved in 90% of patients. In the noninferiority trial, a sustained response was reported in 67% of patients in both the sofosbuvir-ribavirin group and the peginterferon-ribavirin group. Adverse events were less common with sofosbuvir compared to peginterferon. The study concluded that sofosbuvir combined with peginterferon-ribavirin achieved high efficacy and safety in previously untreated patients with HCV infection, particularly those with genotypes 1 or 4.