Abstract: Total thymocyte RNAs were extracted from 4-6 week-old White Leghorn, Langshan, Bigbone, Beijing fatty chicken, Camellia, Xianju and Recessive white feather chickens respectively, mRNAs were isolated from total RNAs using oligo-dT cellulose, then CD4 or CD8α cDNAs were amplified with RT-PCR using the purified mRNAs as the templates. The cDNAs were sequenced after inserted into Promega T easy vector. The sequencing analysis showed that the CD4 sequences of different breeds shared high homology, the CD8α sequences of Chinese local breeds had 6-13 amino acid differences at extracellular domain as compared with those of White Leghorn and RPL line 7. Among Chinese local breeds tested, CD8α sequence of Xianju chicken had 4-5 amino acid differences at extracellular domain as compared with others, while Langshan, Beijing fatty chicken and Recessive white feather chickens share the same sequence of CD8α cDNA. It was shown that the CD4 sequences of Chinese local breeds are highly conserved, while CD8α sequences have lower polymorphism than those of foreign breeds. These results provided useful information for further study on the structure and function of CD4 and CD8 molecules.