ABSTRACT:The effect of the phenotypic combination of genetic variants κ-CN/β-Lg on the contents of technologically and nutritionally important components of milk as well as technological properties of milk was investigated in this paper. The samples of milk were collected from 72 cows of Slovak Pied breed in the second lactation coming from three farms, once from the different lactation stage. The genotyping of milk samples was determined by the horizontal electrophoretic separation of milk proteins on starch gel with addition of urea and mercaptoethanol. Statistical analysis was carried out in the programmes Statistica 6.0 and Statgraphic Plus 5.1 by the least-squares method using the GLM. An non-significant association of B allele in the κ-CN/β-Lg phenotypic combination with milk fat, crude protein content and true protein content was found out. A positive significant effect of κ-CN/β-Lg BB/BB on casein content and casein number was confirmed. The value of casein number increased in the following order: BB/BB > AB/AB > AA/AA (78.43%:77.53%:75.78%). With regard to whey proteins and heat stability, a negative effect of B allele in the phenotypic combination κ-CN/β-Lg was found out.