We have shown that the dominance of CD8⁺ T cells expressing TCR V_β17 in the adult HLA-A*0201-restricted influenza A/M1_58–66-specific response is acquired following first antigen exposure. Despite the acquired dominance of V_β17⁺ cells, subdominant M1_58–66-specific clones expressing non-V_β17⁺ TCR persist in all individuals. To determine whether the affinity of the expressed TCR for the HLA-A*0201/M1_58–66 complex could influence functional properties, M1_58–66-specific clones expressing subdominant (non-V_β17⁺) TCR were compared to cytotoxic T lymphocyte (CTL) clones expressing dominant (V_β17⁺) TCR. The V_β17⁺ CTL required up to 10,000-fold lower amounts of M1 peptide to mediate lysis compared to CTL clones expressing other V_β gene segments. All V_β17⁺ CTL clones tested bound HLA-A*0201/M1_58–66 tetramer, but two of three CTL clones expressing other TCR did not bind tetramer. The inability of non-V_β17⁺ CTL to bind tetramer did not correlate with phenotype, CD8 dependence or with cytokine production profiles. This suggests a limitation for the use of tetramers in examining subdominant T cell responses. Together these findings suggest that V_β17⁺ CTL which dominate the HLA-A*0201-restricted CTL response against influenza A are not functionally distinct from subdominant non-V_β17⁺ CTL. The dominance of V_β17⁺ CTL is likely to result from a competitive advantage due to superior CTL avidity for the HLA-A*0201/M1_58–66 complex.