We and other investigators have revealed an association between Hepatitis C virus (HCV) seropositivity and an increased risk of developing marginal zone B-cell lymphoma (MZ), lymphoplasmacytic lymphoma (LPL, also known as Waldenström's macroglobulinemia), follicular lymphoma (FL), and diffuse large B-cell lymphoma (DLBCL). The sustained virologic response (SVR) to treatment with interferon or pegylated (Peg)IFN with ribavirin was closely associated with the regression of HCV-associated B-cell NHL (mainly MZL, and LPL).