The invasive characteristics of Africanized honey bees in combination with the subtropical location of Puerto Rico are the perfect opportunity to study behavior and hybridization within this island, because it is recognized as a zone ecologically and climatically suitable for Africanized honey bee races but isolated from recurrent introduction of Africanized bees. We will determine rate of European gene introgression to the Africanized bees in multiple loci by use of 14 microsatellites. These markers are selected to be able to compare our results to the published results on Africanized bees in the New World. Hybridization pattern in Puerto Rico seems to be different to the rest of the New World, at least for one locus we examined by Restriction Fragment Length Polymorphism. We found 67.7% of introgression of European alleles in the Island wild Africanized population. In addition, of the four typical African alleles in the same loci, we found only one in the Africanized bees. This result is consistent with a limited or one-time introduction of Africanized bees in Puerto Rico. The optimization test of 10 microsatellite loci with experimental samples from 4 different localities of Puerto Rico (Ceiba, Vieques, Mayaguez and Gurabo), displayed variability in eight markers. Five of these were more variable and the other three had three alleles in four individuals. These preliminary results display some differences in the amplification fragments of some markers in comparison with other studies.