We formulate a model to describe the dynamics of hepatitis C virus (HCV) considering four populations: uninfected liver cells, infected liver cells, HCV and T cells. Analysis of the model reveals the existence of two equilibrium states, the uninfected state in which no virus is present and an endemically infected state, in which virus and infected cells are present. There exists a threshold condition that determines the existence and stability of the endemic equilibrium. We discuss the efficacy of the therapy methods for hepatitis C in terms of the threshold parameter. Success of the therapy could possibly be predicted from the early viral dynamics in the patients.