The aim of this study was to assess the association between liver stiffness measured by transient elastography (FibroScan) and the efficacy of pegylated interferon alpha-2b plus ribavirin combination treatment for patients with chronic hepatitis C virus (HCV) infection. We prospectively studied 145 Japanese patients with chronic HCV infection. FibroScan was done at baseline, at the end of treatment, and at 48 and 96 weeks after the end of treatment. The FibroScan values were significantly decreased for sustained virological response (SVR) patients (the mean rate of change; -16.2%, -32.2% and -43.5%) in comparison with non-SVR patients (-7.2%, -2.1% and +17.3%) at the end of treatment (P=0.0127), and 48 weeks (P<0.0001) and 96 weeks (P<0.0001) after the end of treatment. Among the non-SVR patients, the FibroScan values were significantly decreased for patients with biochemical response (BR) (-17.9%, -30.0% and -27.1%) in comparison with non-BR (-4.1%, +6.4% and +30.6%) at the end of treatment (P=0.0270), and 48 weeks (P<0.0001) and 96 weeks (P<0.0001) after the end of treatment. The FibroScan values may predict a progressively better clinical outcome for patients with successful virological and biochemical responses.