We examined the efficacy and safety of peginterferon (PEG-IFN) alfa-2a plus ribavirin (RBV) therapy for chronic hepatitis C (CHC) patients with genotype 1 and high viral load by multi-center (73 institutions) study in Kyushu and totally 320 patients were enrolled. The sustained virological response (SVR) rates were 53.1% and 59.6% in intention-to-treat and per protocol set analysis, respectively. Treatment prolongation over 48 weeks was more effective in cases which serum HCV-RNA became negative between 13 and 36 weeks after start of therapy. Multivariate analysis for baseline characteristics revealed that age, BMI, total cholesterol and viral load were significantly associated with SVR. However, when added on-treatment factors, early virological response was the only factor associated with SVR. Discontinuation of treatment due to adverse events was no more than 4.5%. In conclusion, PEG-IFN alfa-2a plus RBV treatment to refractory CHC patients is a well tolerated and can achieve over 50% of SVR.