While studying the αβ T cell receptor repertoire in rheumatoid arthritis (RA) patients, we found that the frequency of V_β14⁺ T cells was significantly higher in the synovial fluid of affected joints than in the peripheral blood. In fact, V_β14⁺ T cells were virtually undetectable in the peripheral blood of a majority of these RA patients. β-chain sequences indicated that one or a few clones dominated the V_β14⁺ population in the synovial fluid of individual RA patients, whereas oligoclonality was less marked for other Vβ's and for V_β14 in other types of inflammatory arthritis. These results implicate V_β14-bearing T cells in the pathology of RA. They also suggest that the etiology of RA may involve initial activation of V_β14⁺ T cells by a V_β14-specific superantigen with subsequent recruitment of a few activated autoreactive V_β14⁺ T cell clones to the joints while the majority of other V_β14⁺ T cells disappear.