Background/aim: Chronic hepatitis patients whose HCV RNA became negative at 4 weeks of PEG-Interferon/ribavirin treatment achieved excellent SVR(sustained viral response) rate of almost 90%. However, in patients whose RNA became negative after 20 weeks, the SVR rate is very low. Since many patients became RNA negative at 12-16 weeks, it is important to clarify the characteristics of the patients. Material and Method: Among 234 patients, 41 became RNA negative at 12-16 weeks and the therapy completed (total 48-60 weeks). The characteristics were analyzed by using sex, age, weight, BMI, ALT, GTP, hemoglobin, platelet counts, Ccr, hyaluronic acid, the mutation of HCV core region (aa70, 91) and interferon sensitivity determining region, adiponectine, HOME-IR, RNA dynamics, dose and the treatment period. Result: The SVR rate was 75.6%(31/41). Because all 10 patients of non SVR were female, we compared these 10 patients and 15 female SVR. The platelets counts were low in non SVR (non SVR 15.0 ± 2.8 (x10 4 /mm 3 ) vs SVR 20.2 ± 4.8 (P<0.05)). The mean dose of ribavirin was lower (447 ± 126 mg/day) in non SVR (P<0.05) than in SVR (625 ± 127). Conclusion: As for the characteristics of the patients whose HCV RNA became negative at 12-16 weeks but became non SVR, female, low platelet count and low dose of ribavirin were important factors. In the patients who received reduced ribavirin doses, the idea to increase the ribavirin dose and to maintain it are necessary. (ex, use 400mg and 600mg alternately) PE329 Background: Chronic hepatitis C virus (HCV) infection poses a challenge for a growing number of infected patients who exhibit disease complications, including cirrhosis, hepatocellular carcinoma, and liver failure in China. The combination treatment of peginterferon alpha (PEG-IFN alpha) plus ribavirin (RBV) is recommended as a standard care for HCV infections, which can improves hepatic markers and eradicates the virus in about 50% of patients. However, a significant number of patients do not respond to therapy or relapse following treatment discontinuation. Several viral, hepatic, and patient-related factors influence response to therapy. Methods: In our clinical practice, a total of 77 interferon-naïve patients (61% male; median age 47 years) with chronic hepatitis C include 11 cirrhotic patients (no genotyping) received PEG-IFN alpha-2a 180 mcg/week plus RBV 900-1200mg/day for 48 weeks and follow up 24 weeks. Results: show that the patients have more RVR and EVR rate (54% and 90.9% respectively). While the SVR (undetectable HCV-RNA 24 weeks after treatment completion) rate is only 51.5% In conclusion: comparing with the data of clinical trail, the RVR, EVR and EOTR were higher, while SVR was the same in Chinese patient with chronic hepatitis C patients received the combination therapy of PEG-IFN plus RBV. The reason of high relapse was still unknow. Although optimal duration of retreatment and benefits and safety of maintenance therapy have not been determined, an extended duration is likely needed, even for the patients who achieved EVR.