We explored the link between serum alpha-fetoprotein levels and virologic response in 383 HIV-hepatitis C virus coinfected patients. A low alpha-fetoprotein level (<5.0 ng/ml) was an independent predictor of sustained virologic response (odds ratio = 1.83; 95% confidence interval 1.05-3.20). Serum alpha-fetoprotein measurement should be integrated in the pretreatment assessment of prognostic factors of a virologic response.