Despite of Cundinamarca nearly produces the 27% of the total milk production in Colombia, the quality of this product (protein, fat and total solids) is considered lower than others Colombian regions; which negatively affect the local milk market as the Colombian milk industries pay for high milk quality. Due to this situation, Corpoica have started to implement breeding programs based on molecular marker assisted selection. Under this scheme, genetic polymorphisms associated with bovine milk production traits have been determined, particularly in the variant region of the exon four of the β-lactoglobulin gene (β-LG); which is linked (related) with the casein and fat production. The aim of this study was to estimate the genotypic and allelic frequencies of β-LG by using PCR-RFLP in six different Holstein populations in Cundinamarca. For genotyping analysis a fragment of 247 pb was amplified and then digested using the restriction enzyme Hae III. The results showed that the frequency of allele A (0.51) was similar to allele B (0.49), which is comparable with frequencies values reported for European Holstein cattle. However, the genotypic frequency distribution showed to be different in comparison with those values obtained for worldwide dairy cattle. Thus, AA genotype had the higher frequency (0.35), whereas BB genotype had a lower frequency (0.31). In conclusion, the similar genotypic and allelic frequencies may be related to the absence of breeding programs in Cundinamarca. ; El departamento de Cundinamarca participa con aproximadamente 27% de la producción de leche en Colombia, con desventajas competitivas en cuanto a la calidad del producto (proteína, grasa y sólidos totales); lo cual influye en su participación en el mercado, ya que las empresas lácteas elaboran sus esquemas de pago basándose en estas características de producción. Debido a esta situación, Corpoica ha implementado programas de mejoramiento basados en la selección asistida por marcadores moleculares. Bajo este esquema, se han encontrado ...