Hepatitis C infection is associated with B-cell lymphoproliferative disorders, including mixed cryoglobulinaemia and B-cell lymphoma. A direct pathogenetic role of this infection in lymphomagenesis has been suggested but the molecular basis for viral induced B-cell proliferation is still unknown. We report an unusual case of a patient affected by chronic hepatitis C who presented severe type II cryoglobulinaemia and subsequently lymphoplasmacytoid lymphoma consistent with Waldenstrom's macroglobulinaemia and type I cryoglobulinaemia. In this patient antiviral treatment induced beneficial effects.