The present study was designed to assess the changes in NF-κB DNA-binding activity, IRS-1 expression, and IRS-1 tyrosyl phosphorylation in 3T3-L1 adipocytes after treatment with TSH and then to determine the potential role of TSH in the suppression of IRS-1 expression and tyrosyl phosphorylation, which might contribute to insulin resistance. This evidence concerns the gene IRS1 and Insulin resistance.