The data demonstrate that cows with the genotypes κ- casein BB and β-lactoglobulin BB produce milk with a protein composition that is favorable for increased cheese yield. For proportions of αS1-casein, κ-casein, and β-lactoglobulin in total milk protein, κ-casein and β-lactoglobulin genotypes explained more than 50 and 25% of the heritability and repeatability estimates, respectively, and more than 14% of the phenotypic variance. Diet had only a minimal effect on milk protein composition. In conclusion, increasing cheese yield through modification of milk protein composition can be achieved most rapidly by selection for cows with κ-casein BB and β-lactoglobulin BB genotypes.