The present invention relates to 2-Methyl Substituted Nucleoside Derivatives of Formula (I): and pharmaceutically acceptable salts thereof, wherein B, R1, R2 and R3, are as defined herein. The present invention also relates to compositions comprising at least one 2-Methyl Substituted Nucleoside Derivative, and methods of using the 2-Methyl Substituted Nucleoside Derivatives for treating or preventing HCV infection in a patient.本發明係關於式(I)之2-甲基經取代之核苷衍生物,及其醫藥上可接受之鹽,其中B、R1、R2及R3係如本文所定義。本發明亦係關於包含至少一種2-甲基經取代之核苷衍生物之組合物,及使用該等2-甲基經取代之核苷衍生物用於治療或預防患者之HCV感染之方法。