The aim of our study was to get information on the immune status of patients who undergo haemodialysis in the presence of an HCV infection. This virus infects not only hepatocytes, but also blood mononuclear cells, in particular B cells , but we do not know the role of this lymphocyte involvement in the maintenance and progression of hepatitis. The impairment of the cell-mediated immune response in uraemic patients is well known, for example only 50–60% of uraemic patients undergo a seroconversion after HBV vaccine, compared to 95% of the normal population. Paradoxically the immunodeficiency is concomitant with an activation of related cells which is increased rather than ameliorated by the dialysis treatment . In these patients lymphocytopenia is also present with a reduction of the absolute number of T lymphocytes which remain normal in percentage. The study was performed on the following groups of subjects.