Although the single-nucleotide polymorphism (SNP) rs12979860 in the IL28B gene is a better predictor of sustained virological response to treatment of chronic hepatitis C (CHC) than other baseline factors, some CHC patients with the favorable C allele cannot achieve a sustained virological response when treated with peginterferon plus ribavirin. The aim of this study was to examine baseline factors as predictors of rapid virological response (RVR) and complete early virological response (cEVR) to peginterferon alfa-2a plus ribavirin treatment in Chinese CHC patients with hepatitis C virus (HCV) genotype 1b, with emphasis on the difference between the rs129860 CC and CT/TT genotypes. A total of 337 treatment-naïve patients participated in this study. All patients were treated with peginterferon alfa-2a plus ribavirin at standard dosage. Serum samples from all patients were collected at baseline, week 4, and week 12 for testing of laboratory parameters, and IL28B genotypes were determined. Multivariate analysis showed that among rs12979860 CC genotype patients, glucose level and aspartate amino transferase (AST) activity were inversely associated with RVR, while abnormal platelet count and allergy inversely associated with cEVR. Among rs12979860 CT genotype patients, age below 40 years and short infection duration were associated with RVR, while age below 40 years, short infection duration, high body mass index (BMI), and no history of allergies were associated with cEVR. The baseline factors associated with the response to CHC treatment may depend on the IL28B genotype. Refinement of the baseline predictors based on IL28B genotypes may be useful for management of HCV infection.