Over the last decade it has become evident that in addition to producing antibody, B cells activate the immune system by producing cytokines and via antigen presentation. In addition, B cells also exhibit immunosuppressive functions via diverse regulatory mechanisms. This subset of B cells, known as regulatory B cells (B regs), contributes to the maintenance of tolerance, primarily via the production of IL-10. Studies in experimental animal models, as well as in patients with autoimmune diseases, have identified multiple B(reg) subsets exhibiting diverse mechanisms of immune suppression. In this review, we describe the different B(reg) subsets identified in humans, and their diverse mechanisms of suppression in HCV and diabetic patients. Aims: The main objectives of the study are to identify the role of B (reg) in the hepatitis C virus infected patients and diabetes.