DQA1, DQB1 and DPB1 alleles were investigated in a large panel of samples carrying HLA‐DQ2‐ and HLA‐DQ9‐bearing extended haplotypes. Every instance of the [HLA‐B8, SCO1, DR3, DQ2a] and [HLA‐B18, F1C3, DR3, DQ2b] extended haplotypes carried the DQA1*‐0501 allele, while every instance of [HLA‐844, F1C31, DR7, DQ2c], (HLA‐B47, FC91,0, DR7, DQ2c] and [HLA‐B57, SC61, DR7, DQ2d] carried the DQA1*0201 allele. All HLA‐DR3, DQ2 and HLA‐DR7, DQ2 extended haplotypes carried the DQB1*0201 allele. Every example of [HLA‐B57, SC61, DR7, DQ9] carried the DQB1*0303 allele. Several associations between the DPB1 alleles and some HLA‐DQ2‐ and DQ9‐carrying extended haplotypes were identified. HLA‐DPw2‐encoding alleles. DPB1*0202 (50%, p<0.001) and 0201 (30%). were found on the [HLA‐B18, F1C30, DR3, DQ2b] extended haplotype. Every instance of the [HLA‐B57, SC61, DR7, DQ9] extended haplotype carried the DPB 1*0401 allele. Also, we have confirmed the associations of the DPB1*0101 and DPB1*0401 alleles with the [HLA‐B8, SC01. DR3, DQ2a] extended haplotype. The analysis of hornozygous typing cells carrying the [HLA‐B44. FC31, DR7, DQ2c] extended haplotype showed that the DPB1*0401 and 0201 alleles were present at similar frequencies (37.5%). while the DPB1*1101 allele was found in only 25% of these haplotypes analyzed. Our results suggest that the constancy of the DNA of the HLA‐B, DR, DQ regions may extend to the DP region and that the extent of such fixity varies, perhaps as the result of