There are few surveillance studies analyzing genotypes or primary (transmitted) drug resistance in HIV-infected blood donors in Brazil. The aim of this study was to characterize patterns of HIV genotypes and primary resistance among HIV seropositive donors identified at 4 geographically dispersed blood centers in Brazil.Of the 341 HIV seropositive donors who consented to participate in the risk-factor and genetics study, pol sequences were obtained for 331 (97%). Clade B was predominant (76%) followed by F (15%) and C (5%). Primary resistance was present in 36 (12.2%; 95% confidence interval [CI] 8.2,15.5) of the 303 individuals not exposed to antiretroviral therapy (ART), varying from 8.2% (95%CI 2,7,13.6) in Recife to 19.4% in São Paulo (95%CI 9.5,29.2); there were no significant correlations with other demographics or risk factors.