Background/Purpose Alcohol use may have negative impacts on hepatitis C virus (HCV) treatment due to low adherence, and racial differences can influence HCV sustained virological response (SVR) rate between East Asian and European ancestry. The objective of this study is to confirm the influence of alcohol consumption and racial differences on HCV treatment outcome in aboriginal and nonaboriginal people of southeastern Taiwan. Methods In this retrospective cohort study, a total of 195 patients were treated with peginterferon-alpha once weekly plus ribavirin for 24 weeks. The efficacy analysis was performed based on the SVR rate for patients who received at least one dose of the study medication or who completed treatment. The endpoints were denoted by virological response rate including the influences of alcohol use, HCV genotype, serum level of HCV virological load, and racial differences. Results No differences were observed in the baseline clinical characteristics between drinkers and nondrinkers, but a significant difference was noted in the body mass index between aboriginal and nonaboriginal populations (28.3 vs. 25.8; p < 0.01). With respect to the SVR rate, no difference was found between drinkers and nondrinkers, and between aboriginal and nonaboriginal people. The treatment efficacy of SVR in the whole group was significantly different between patients with HCV genotype 1 and nongenotype 1 (73.5% vs. 91.2%; p < 0.01). An analysis of the SVR rate in the aboriginal group showed no significant difference between patients with genotype 1 and nongenotype 1 (80.0% vs. 91.3%; p = 0.31). Conclusion In southeastern Taiwan, alcohol consumption did not influence the HCV treatment outcome, and the SVR rates were similar between patients with HCV genotype 1 and nongenotype 1 infections in the aboriginal group.