Serum levels of free T3(FT3), free T4(FT4), total T3(TT3), total T4(TT4) and TSHIRMA were measured in 43 and 67 normal subjects and 14 uremic patients, and 21 patients receiving hemodialysis. Significantly lowered mean serum FT4 FT4 and TT3 but normal T4 and TSHIRMA were observed in uremic and hemodialysis ones, although all subjects were in the state of euthyroidism, The rates of low FT3, FT4, TT3 and TT4 were 37.5%, 42.9%, 50% and 21% in uremic patients and 81%, 38.1%, 61.9% and 14.2% in hemodialysis patients, respectively. The postdialysis TSHIRMA level was significantly reduced and FT3, FT4, TT3 and TT4 were unchanged after one hemodialysis. There was no change of the rates of low FT3, FT4 TT3 and TT4 in the course of repeated dialysis.The conclusion is that FT3, FT4, TT3 and TT4 are lowered in most uremic and hemodialysis patients while TSHIRMA is normal or only slightly lowered. The thyroid function of them is most likely normal (euthyroid). TSHIRMA is a useful index in diagnosing hypothyroidism in uremic and hemodialysis patients. Transient and maintained hemodialysis do not dramatically change the thyroid hormones and TSHIRMA levels.