We investigated DR52 haplotype polymorphism in a population of 78 Croatian families with at least one parent and one offspring positive for a DR52-associated allele, using the PCR-SSOP method. The haplotypes DRB1*0301-DQA1*0501-DQB1*0201, DRB1*11-DQA1*0501-DQB1*0301 and DRB1*1201-DQA1*0501-DQB1*0301 seem to be conserved haplotypes in this Croatian population, while DRB1*13 haplotypes showed high diversity. Among 10 different DRB1*13 haplotypes, four consist of common alleles, while six have an unusual combination of DRB1-DQA1-DQB1 alleles. Three haplotypes (DRB1*1301-DQA1*0103-DQB1*0503, DRB1*1302-DQA1*0102-DQB1*0502 and DRB1*1303-DQA1*0102-*DQB1*0502) have not been reported. These results on DR52-associated haplotype polymorphisms in a Croatian population must be taken into consideration in organ transplantation, especially when searching for unrelated bone marrow donors.