The putative role of hepatitis C virus (HCV) infection in the pathophysiology of lymphoproliferative diseases (LPD) is supported by North American and southern European studies reporting high HCV seroprevalence in patients with B-cell-non-Hodgkin lymphoma (NHL). In order to evaluate the situation in France, we conducted a retrospective national study about the association of chronic HCV infection and LPD. 72 Internal Medicine and Infectious Diseases departments were contacted. Response rate was 51.4%. We recorded 43 LPD (19 males, 24 females): 31 B-cell-NHL, 4 Waldenstro Β¨m's macroglobulinemia, 3 chronic lymphocytic leukemia, 2 multiple myeloma, 2 lymphomas of the mucosaassociated lymphoid tissue, and 1 Hodgkin's disease. Mean age at HCV diagnosis was 62 years (range 33-84). In 16 cases, LPD occurred in patients known to be HCV-infected. For 11 patients, LPD diagnosis preceded the diagnosis of HCV infection, whereas diagnosis was done simultaneously in 11 patients. For those with accurate infection date, mean interval between both events was 15.2 years. Fourteen patients had HCV extrahepatic manifestations: 9 mixed cryoglobulinemia, including 7 with NHL, 5 sicca syndrome (5 NHL), and both in one patient. Cohort of HCV-infected patients could be accurately determined for 16 departments, totaling 1,485 patients and 37 cases. Thus, from our data the frequency of LPD among HCV-infected patients approximates 2.49%. Despite possible bias inherent to this retrospective study, our data support the hypothesis of HCVassociated LPD and particularly B-cell-NHL. In France, this association is much lower than in Italy. Further studies are needed to assess the precise role of HCV in the multistep process leading to monoclonal proliferation. Am.