Because of the different observed results about the microproteinuria in autoimmune thyroid disease, serum B2-MG, urine B2-MG, albumin and immunoglobin by RIA in 39 untreated autoimmune thyroid disease (AITD) (28 with Graves disease and 11 with Hashimoto disease) had been observed. Micro-proteinuria was found in 28.6% of patients with Graves disease and in 45.5% with Hashimoto disease; Serum B2-GM concentrations were significantly increased in Graves disease compared with that of controls. Our results suggest that the lesions present in both glomerulus and tubulus in AITD. The mechanism of them had been discussed in this paper.