Patients with Graves’ disease (GD) have marked lymphocytic infiltration in their thyroid glands We examined the gene for the variable regions of the α chain of the Chinese T cell receptor(V α gene) in intrathyroidal T cells to determine the role of T cells in the pathogenesis of GD and offer potential for the development of immunotherapeutic remedies for GD Methods. We used the reverse transcription and polymerase chain reaction(RT PCR) to amplify complementary DNA(cDNA) for the 18 known families of the V α gene in intrathyroidal T cells from 5 patients with Graves’ disease The findings were compared with the results of peripheral blood T cells in the same patients as well as those in normal subjects Results. We found that marked restriction in the expression of T cell receptor V α genes by T cells from the thyroid tissue of Chinese patients with GD(P<0 001) An average of only 4 6±1 52 of the 18 V α genes were expressed in such samples, as compared with 10 4±2 30V α genes expressed in peripheral blood T cells from the same patients The pattern of expressed V α genes differed from patient to patient with no clear predominance Conclusions. Expression of intrathyroidal T cell receptor V α genes in GD is highly restricted suggesting the primacy of T cells in causing the disorders Patients with Graves’ disease (GD) have marked lymphocytic infiltration in their thyroid glands We examined the gene for the variable regions of the α chain of the Chinese T cell receptor (Vα gene) in intrathyroidal T cells to determine the role of T cells in the pathogenesis of GD and offer potential for the development of immunotherapeutic remedies for GD Methods. We used the reverse transcription and polymerase chain reaction (RT PCR) to amplify complementary DNA (cDNA) for the 18 known families of the V [alpha] gene in intrathyroidal T cells from 5 patients with Graves’ disease The findings were compared with the results of peripheral blood T cells in the same patients as well as those as in normal subjects Results. We found that marked restriction in the expression of T cell receptors V α genes by T cells from the thyroid tissue of Chinese patients with GD (P <0 001) An average of only 4 6 ± 1 52 of the 18 V α genes were expressed in such samples, as compared with 10 4 ± 2 30 V α genes expressed in peripheral blood T cells from the same patients The pattern of expressed V α genes differed from patient to patient with no clear predominance Conclusions. Expression of intrathyroidal T cell receptor V α genes in GD is highly restricted suggesting the primacy of T cells in causing the disorders