Bovine tick parasitism is a determinant of estimated losses of US $ 3.4 billion annually in Brazil. Much of these losses are due to mistakes made in the controlling attempts. The three main mistakes made are the use of an inappropriate acaricide at the wrong time and in the wrong way. In view of this situation, Embrapa Dairy Cattle implemented the acaricide effectiveness testing, a free service based on the determination of the most suitable product for application in each property, based on samples sent by the farmers. From 1997 to the present, approximately 6,000 tests have been carried out, which, if on the one hand are a source of information and help to the farmer, on the other hand represent a form of updated and real knowledge about the state of the art of tick resistance of cattle to the main chemical bases available. This knowledge, however, has been limited to the phenotypic resistance profile of ticks. Another limitation refers to the period required to carry out the test, 35 days, which does not match the urgency of the farmer to obtain the necessary guidance for the implementation of an efficient control. Therefore, the present project was designed with the objectives of carrying out the molecular characterization and drawing a genetic profile of the resistance of cattle tick populations in the state of Minas Gerais to the main chemical bases available and also validating and training the Laboratory of Parasitology to perform a test to assess sensitivity by means of PCR (Polymerase Chain Reaction). Samples of ticks from several municipalities in the State of Minas Gerais were subjected to the engorged female immersion test to assess sensitivity to the main available chemical bases. DNA was extracted form larvae belonging to the control group and form hemolymph from engorged females from each sample. The extracted DNA was genotyped for the presence of resistance / susceptibility alleles to each of the chemical bases by means of a PCR according to the desired target. From the results obtained, the worrying scenario of the resistance of tick populations to the main available acaricide chemical bases, which was already known phenotypically, was confirmed genotypically, adding the predominant heterozygous character of thick resistance to pyrethroids. Although further studies are still needed to enable the implantation of a test to assess sensitivity by means of PCR, the results obtained in this research contribute to elucidate the genotypic profile of resistance, reflecting advances in the establishment of strategies for the control of bovine ticks.