The aim of the thesis is to study the influence of the milk protein beta-lactoglobulin on the milk renneting properties. Based on the polymorphisms in -lactoglobulin gene (BLG), the genotypes AA, AB and BB were defined by the method PCR-RFLP in the case of 730 dairy cows. The results of the genotypes analysis show that in the studied population the heterozygotes AB occur approximately eleven times more often than homozygotes BB and thirty times more often than homozygotes AA. The allele A frequency was 0.4732 and the allele B 0.5268. The genotype BLG influence on production traits of milk was analysed in the aggregate of 429 milk samples. The statistically demonstrative allele B influence on the percentage of proteins representation was found only in one group of dairy cattle from farm Sedlec. The alleles BB were associated with lower values of these parameters. The statistically significant difference influenced by the genotypes or the gene BLG alleles was not found in any other measurement. In the thesis the testing of milk renneting properties by the rennet coagulation time (RCT) and the determination of titratable acidity in milk was made on 51 samples. The results show that the BLG genotypes had no influence on the RCT. In the determination of titratable acidity in milk results the genotype influence appeared and the p-value is lower than the given significance level = 0.05. It could mean that the AB genotype is connected with the higher milk acidity. However, the results can be distorted by the low numbers of the population.