An association of hepatitis C virus (HCV) with low-density lipoproteins (LDL) in serum of patients with chronic hepatitis C (CHC) has been suggested. We conducted a prospective study in CHC patients complicated with hyperlipidaemia, to examine whether bezafibrate, which is commonly used for treatment of hyperlipidaemia, reduces serum HCV-RNA titre and improves liver dysfunction. Fifteen patients received daily oral bezafibrate treatment (400 mg/day) for 8 weeks, and its effects on serum lipids, transaminases, HCV-RNA titres, and HCV-RNA titres bound to LDL were evaluated. Fifteen untreated patients with CHC and hyperlipidaemia were used as controls. The mean serum alanine aminotransferase levels and HCV-RNA titres significantly decreased at the end of bezafibrate therapy in the treated group (105 +/- 34 to 80 +/- 32 IU/L, P = 0.02 and 2.23 +/- 2.71 to 1.78 +/- 2.38 x 10(7) copies/mL, P < 0.01 respectively), but no changes were observed in the control group. Serum HCV-RNA titres bound to LDL, as quantified by immunoprecipitation using anti-LDL antibody, also decreased in all 15 treated patients [5.55 +/- 6.59 to 1.07 +/- 1.58 x 10(6) copies/ml, P < 0.01 (mean reduction rate was -78.5 +/- 17.0%)]. Sucrose density-gradient ultracentrifugation study revealed that HCV-RNA-decreased density fractions after the bezafibrate were identical to LDL-density fractions (1.015-1.062 g/mL). Eight CHC patients were treated with bezafibrate, interferon, and ribavirin triple therapy for 32 weeks, and four patients achieved sustained virological response to therapy. This pilot study provides further evidence of an association between HCV and LDL in serum and suggests the potential usefulness of bezafibrate as an anti-HCV reagent for the treatment of CHC patients.