Brucellosis is a zoonosis of worldwide importance. In animals it is known as infectious abortion, contagious abortion, epizootic abortion and Bang's disease in cattle. In humans it is known as Melitococcosis, undulant fever, Malta fever, Mediterranean fever. In the present work, the antibodies formed against Brucella abortus in cattle were determined, as an effect of the inoculation of two types of vaccines, Strain RB51 and CEPA19, to dairy cattle from the High Valley and Central Valley. The antibodies were detected by means of two laboratory techniques of different principle: ELISA and Fluorescence Polarization Assay (FPA).60 blood samples were taken at random from animals that received vaccine 21days in advance, the samples taken were distributed as follows: 15 calves, 15 heifers, 15 heifers and 15 adult cows. All samples were assayed, in parallel, by means of the two techniques indicated, Fluorescence Polarization Test and competitive ELISA.