Background: Aedes aegypti is an urban mosquito vector of Dengue and other arboviruses. During epidemic periods, pyrethroid insecticides are used for the control of adult mosquitoes; the worldwide distributed resistance to these insecticides is a cause of failures in vector control campaigns. The primary target of pyrethroids is the voltage-gated sodium channel; point mutations on this channel, called kdr mutations, are associated with pyrethroid resistance. Two kdr mutations, called V1016I and F1534C, augmented in frequency in natural populations of Ae. aegypti from the Americas in the last decade. The diagnostic of kdr polymorphisms allows an early detection of insecticide resistance spreading, which is critical for timely decisions on vector management. Given the relevance of resistance management, high-throughput methods for kdr genotyping are invaluable tools for resistance monitoring programs. These methods should also be cost-effective, to allow regional-scale surveys. Despite the extended presence of Ae. aegypti and the incidence of dengue in Argentina, the presence, abundance and distribution of kdr mutations were not reported in this country up to date. Methodology and findings: We report a multiplex high-throughput assay based in High Resolution Melting PCR for the simultaneous genotyping of 1016 and 1534 sites in voltage-gated sodium channel gene. We used this method for the study of individual mosquito samples collected in localities which received different selection pressure with pyrethroids. Compared to other genotyping methods, multiplex High Resolution Melting was high-throughput, cost-efficient, sensitive and specific. We demonstrate for the first time the presence of kdr mutations in Argentina in regions under different selection pressure with pyrethroids. Conclusions and Significance: We have developed a high-throughput method for the genotyping of alleles associated with pyrethroid resistance in Ae. aegypti from the American continent. The method developed here is comparable in its sensitivity and reliability with other genotyping methods, but reduces costs and running time. It could be incorporated in control campaigns for control the presence and spreading of resistance-associated alleles. We report here for the first time the presence of kdr mutations in distant populations from Argentina, with different epidemiological situations and different history of mosquito control efforts.