OBJECTIVE--To assess the nature of T cell receptor (TCR) utilisation by CD4 T cells in the rheumatoid joint. METHODS--Sequencing of the joining (NDJ) region of TCR beta chain mRNA isolated from synovial fluid CD4 T cells was performed in three patients in order to determine if oligoclonal expansion of particular sequences was present. Two patients were studied longitudinally to determine if these sequences changed over time. RESULTS--A number of dominant clonotypes were found within the TCR transcripts sequenced in each patient. In the two patients who were studied longitudinally, different dominant clonotypes were detected over time. No single clonotype was persistently dominant during the period of study. CONCLUSIONS--The pattern of TCR usage showed multiple oligoclonally expanded CD4 T cells within the rheumatoid joint. The change in clonotypes within the joint over time suggests that different antigens may be able to elicit synovial inflammation during the course of rheumatoid disease.