OBJECTIVE: To provide cost-effectiveness evidence among: 1) no antiviral treatment; 2) interferon £\-2b (IFN) 3MU, plus ribavirin (RBV) >10.6 mg/kg/day; 3) peginterferon £\-2b (PEG-IFN) 1.5 £gg/kg, plus RBV >10.6 mg/kg/day for 24 weeks for the treatment of patients with Chronic Hepatitis C. METHODS: A two-year decision-tree modeling technique was used. Direct medical costs were collected using local physician practice patterns and reimbursed price. Outcome measure was sustained virological responder gained. RESULTS: For overall genotyping, the 2-year average costs of IFN a-2b plus RBV therapy was US$ 3859. The efficacy data from Taiwan indicated that for overall genotyping, the sustained virological response (SVR) of IFN a-2b plus RBV and PEG-IFN a-2b plus RBV was 63.6% and 67.1%, respectively. In genotype-1 patients the data was 41.0% and 65.8%, and in genotype 2/3 patients it was 86.8% and 68.4%, respectively. The efficacy data were different between Taiwan and international society. The study used the incremental cost of US$ 12,500 per sustained virological responder gained (ICER) as the criterion for judging the cost effectiveness. In Taiwan, for overall patients or differentiate between genotype 1 or 2/3 patients, combination therapy for 24-week all showed cost-effective than no antiviral therapy. In genotype-1 and for overall patients, PEG-IFN combination therapy for 24 weeks showed cost-effective than IFN combination therapy; however, in genotype 2/3 patients, IFN combination therapies for 24 weeks showed cost-effective than PEG-IFN combination therapy. For patients with good drug compliance, both combination strategies showed cost effectiveness. From overall patients, the data indicated that PEG-IFN/IFN cost ratio may reaches 4, and in genotype 1 patients, the cost ratio may reaches 9 could still have ICER value less than US$ 12,500. CONCLUSION: PEG-IFN plus RBV treatment modality is a cost-effective strategy for the treatment of naïve patients with chronic hepatitis C, especially type 1 patient.