T-cell receptors (TCRs) recognize foreign antigens in the context of major histocompatibility complex (MHQ-encoded cell surface proteins. These receptors are heterogeneous, dimeric glycoproteins composed of disulphide linked α- and β-chains. We analysed the diversity of TCRs in a collection of H-2Kb-restricted, 2,4,6-trinitrophenyl (TNP)-specific (H-2K b/TNP) cytotoxic T-cell (Tc) clones from C57BL/6 mice. Investigation of the β-chain messenger RNAs revealed that nearly half of these independent clones expressed an identical β-chain gene1. We show here that almost all the Tc clones expressing the predominant β-chain gene also express an identical α-chain gene. These results show that a strong selective pressure acted on the Tc population, resulting in a skewing of the TCR repertoire for H2Kb/TNP and in the dominant expression of one TCR with this specificity. Possible explanations for this skewing include antigen-driven clonal expansion and network interactions.