Purpose: The purpose Of this study was to investigate a possible relationship between human leukocyte antigens (HLAs) DRB1 and DQB1, dental caries, and colonization by mutans streptococci (MS) in children. Methods. Sixty children were clinically examined for caries in accordance with World Health Organization criteria and methods. Thereafter, subjects were assigned into 2 groups: (7) high-caries children (dft and DMFT >= 5), and (2) caries-free children (dft and DMFT=0). Fresh saliva samples were collected and tested for mutans streptococci, after which the subjects were placed into 2 groups, having either high (>= 10(5) colony-forming units [CFU]/mL saliva) or low (<10(5) CFU/mL saliva) numbers of micro-organisms in saliva. The polymerase chain reaction/sequence specific primer method was used to determine HLA DNA typing from fresh blood samples. Results. There was no significant difference between the frequency of HLA alleles in high-caries and caries-free subjects. Although chi-square test suggested an association for HLA-DRB1*01 and HLA-DQB1*03 with the salivary numbers of MS (P=.025 and P=.009, respectively), these could not be confirmed by logistic regression analysis (P=.188 and P=.101, respectively). Conclusions: The results obtained fail to establish on association between human leukocyte antigen alleles DRB1 and DQB1 and salivary numbers of MS in the selected child population.