There are no univocal experimental data in literature about T cell clone alterations in the peripheral blood during Hashimoto's thyroiditis (TH), autoimmune disease, and during subacute thyroiditis (TSA), an inflammatory thyroid lesion with possibility of "self-perpetuation". The object of our research was to examine the T cell clones, soluble fraction of interleukin 2 receptor and HLA-DR modifications in patients with TH and TSA compared with healthy population. Our results show significant increase of sIL-2r in the TSA compared with normal subjects and with patients TH, where on the contrary, a constant increase of HLA-DR was observed.