The role of T reg cells in chronic HCV infection highlights the application of their manipulations in HCV associated clinical situations. Their suppressive activityis limited to the biologically important compartment. Thus, the ratio of virus-specific CD8+ cells versus CD4+CD25+ T reg cells that is required for a strong suppression mirrors the intrahepatic situation. Assaying these cells marks the etiology of extrahepatic manifestations, asymptomatic MC in patients with chronic HCV and elucidate a correct way for treatment. Meanwhile, this book which is based on a research study conducted in Egypt clarified that an elevated s. level of cryoglobulins was diagnostic for MC as an auto immune disorder associating chronic HCV. Such elevation of was indicative for an auto immune process which is a common complication for chronic HCV infection. T reg cells assay in chronic HCV patients who developed HCC is investment of the advantage of its lowering or depletion in such patients. Consequently,the depletion of T regs represents a tool for treatment of cancer, enhancement of the tumor vaccines & new therapeutic strategies via stimulation of HCV-specific immunity.