BACKGROUND: Prior investigation has identified factors associated with response to treatment in hepatitis C including viral genotype and titre, body weight, hepatic fibrosis, and adherence to therapy. The lower response rate of African-Americans relative to whites has been previously described, but studies of other racial or ethnic groups remain limited. OBJECTIVE: To determine whether Asian race is an independent marker for response to antiviral therapy in hepatitis C. METHODS: Data on treatment-naïve patients from a large multicenter study of combination therapy with peginterferon alfa-2a (180 μg SC each week) and ribavirin (800 mg daily) were analyzed retrospectively to identify factors associated with an SVR, defined as an undetectable serum HCV RNA at least 24 wk after completion of therapy. RESULTS: SVR occurred in 45% of 384 whites and 65% of 52 Asians (P = 0.0047) who were treatment naïve. In a multivariate logistic regression analysis that adjusted for all the aforementioned factors known to be associated with treatment response, Asian race was shown to be an independent predictor of achieving an SVR (OR 2.22, 95% CI 1.11-4.46). Other independent predictors of SVR include viral genotype, body mass index, degree of hepatic fibrosis, and adherence with ribavirin. CONCLUSIONS: Asians are more likely to achieve an SVR to treatment with peginterferon alfa-2a and ribavirin than whites with chronic hepatitis C, suggesting a genetic influence on the antiviral response.