T cell antigen specificity is determined by the products of the genes which encode the variable regions of their receptors. Of the T cell receptor (TCR) variable region gene products examined, only Vβ6.7a TCR‐positive lymphocytes were reduced in primary Sjogren's syndrome patients with IgG 1 hypergammaglobulinaemia compared with an age‐, sex‐ and HLA‐matched control population. The levels of Vβ6.7a T cells were also significantly reduced when these patients were compared with an age‐ and sex‐matched but HLA‐unmatched control group and non‐tissue typed normal people of both sexes. Since published studies show no such abnormality in rheumatoid arthritis, systemic lupus erythematosus or other autoimmune diseases, this abnormality may reflect a pathogenic process specific to primary Sjogren's syndrome.