The objective of the study was to identify an association between the genotypes of BoLA-DRB3.2 loci (*16/- and *23/-) and occurrence of sub-clinical mastitis or latent mammary gland infections caused by different bacterial species in dairy cows. Blood was withdrawn from of 275 cows from two Polish dairy herds, and animals were genotyped for BoLA-DRB3.2*16 and BoLA-DRB3.2*23 using MPTPCR technique. The bacteriological status of the mammary gland was determined by collecting and culturing composite milk samples. SCC was recorded by Fossomatic device after bacteriological examination. No relationship was identified between cows of *16/- or *23/- Bola-DRB3.2 genotype In susceptibility/resistance to sub-clinical mastitis caused by Staphylococcus aureus. However, genotype *23/- was found to be associated (P≤0.01) with increased susceptibility to sub-clinical mastitis caused by Streptococcus dysgalactiae.