The aim of this study was estimate the relations between CRH C22G and milk production traits (milk yield, yield of protein and fat, content of protein and fat in milk). The study was carried on 169 Polish Holstein-Friesian strain Red-and-White cows kept in the south-western region of Poland. The CRH C22G (exon 2) polymorphisms were detected using PCR-RFLP method. The genotype and allele frequencies were estimated and they were as follows: CC - 0.89, CG - 0.09, GG - 0.02; C - 0.93, G - 0.07. Statistically significant (P < or = 0.05) associations between CRH C22G genotypes and milk production traits like milk yield and protein yield in the second lactation were found. Moreover, the obtained results should be verified by conducting research on a larger group of animals and various cattle breeds.