A total of 76 different nucleotide acid sequences of MHC gene,which were classed as 20 alleles,were identified in 185 clones from 16 resistant and 21 susceptible “whole red” color patterns of Cyprinus carpio var.color individuals using the specific primer pair of DABF and DABR.The 624 bp-long nucleotide fragment consisted of the exon1,exon2,exon3 and exon4,encoding signal peptide,β1 domain,β2 domain and part transmembrane,respectively.There were 144 nucleotide(52.17%)and 70 amino acid(76.07%)variable sites in the 276 bp-long β1 domain,whereas the nucleotide and amino acid variable sites were 98(34.75%)and 50(53.19%)in the 282 bp-long β2 domain.It was obviously found that β1 domain had more variable sites than β2 domain.Meanwhile,23 variable sites were observed in total 24 peptide binding residues(PBR)of β1 domain.The ω-values(ω=d_N/d_S)were 1.367,0.886,and 0.754 for PBR and non-PBR of the β1 domain,and for β2 domain,respectively,implying positive selection pressure conducted on the MHC-DAB gene(especially for β1 domain)of C.carpio var.color.The percentage(13.75%)of Cyca-DAB3*15 was significantly higher in the resistant stock than that(3.81%)in the susceptible stock(P<0.05).Interestingly,the Cyca-DAB3*09 and CycaDAB3*10 were only found in the resistant stock,with percentage of 3.75%(P<0.05),whereas the Cyca-DAB3*02 and Cyca-DAB3*14 were only observed in the susceptible stock,with the percentage of 7.62%(P<0.05)and 8.57%(P<0.01),respectively.The present results would be useful to conduct the disease-resistant breeding program in the C.carpio var.color.