Objective: Even if the liver represents the most important target of viral replication, it has also been demonstrated that HCV is able to infect and replicate in some cell subsets involved in the immune response, such as peripheral blood mononuclear cells (PBMCs). More recently, the possible role of viral replication in PBMCs in patients with chronic hepatitis C (CHC) receiving antiviral treatment has been debated. For this reason, we aimed to study the frequency of HCV RNA persistence in serum and PBMCs of patients with CHC who were under treatment of combination antiviral therapy with peginterferon alfa and ribavirin. Materials and Methods: Fifty five patients with CHC were included in this study. Based on their treatment schedules, the patients were divided into three groups. Group I consisted of 22 patients who had not received any treatment. Group II were 18 patients under treatment of peginterferon alfa and ribavirin. Group III consisted of 15 patients who completed a full course of antiviral therapy. Blood samples were collected from all the patients. RNA was extracted from the plasma and cells and the subjected to a quantitative real-time PCR. Results: Persistent HCV infection, defined as the presence of HCV RNA in PBMC, was present in two of the 15 patients (13%) 6 months after the end of the treatment. HCV-RNA copy number in PBMCs of two patients was 1700 and 1300 copies/10^8 PBMCs, respectively. HCV-RNA was not detected in any of the 15 serum samples collected from this group of patients. Rapid virological response was noticed in the serum samples about 6 weeks after the treatment. Overall, HCV-RNA viral load in the serum samples was higher than in PBMCs in untreated patients and during antiviral therapy. Conclusion: Our results indicate that, HCV-RNA may persist in the PBMCs after sustained antiviral treatment in some patients with chronic hepatitis C virus infection. It is possible that viral persistence and, more specifically, the presence of HCV-RNA in PBMC may lead to HCV reactivation.