Abstract We describe for the first time extended haplotypes in a Croatian population. The present study gives the HLA-A, -B, -DRB1, -DQA1 and -DQB1 allele and haplotype frequencies in 105 families with at least two offspring. All individuals were studied by conventional serology for HLA class I antigens (A and B), while class II alleles (DRB1, DQA1, DQB1) were typed using the PCR–SSOP method. HLA genotyping was performed by segregation in all 105 families. For extended haplotype analysis, 420 independent parental haplotypes were included. Fourteen HLA-A, 18 HLA-B, 28 DRB1, 9 DQA1 and 11 DQB1 alleles were found in the studied population. Most of the DRB1 alleles in our population had an exclusive association with one specific DQA1-DQB1 combination. This strong linkage disequilibrium within the HLA class II region is often extended to the HLA-B locus. A total of 10 HLA-A, -B, -DRB1, -DQA1, -DQB1 haplotypes were observed with a frequency ≤ 1.0%. The three most frequent haplotypes were HLA-A1, B8, DRB1*0301, DQA1*0501, DQB1*0201; HLA-A3, B7, DRB1*1501, DQA1*0102, DQB1*0602 and HLA-A24, B44, DRB1*0701, DQA1*0201, DQB1*02. These results should provide a useful reference for further anthropological studies, transplantation studies, and studies of associations between HLA and diseases.