Thiazole-Zn is a systemic fungicide synthesized and developed in China that has been used for the prevention and treatment of bacterial and fungal diseases on fruits and vegetables. Thiazole-Zn is a new?thyroid?disruptor chemical. The purpose of this study was to clarify the?thyroid-disrupting?property of thiazole-Zn and the?mechanism?responsible for?thyroid?hormone (TH) biosynthesis inhibition in?male?rats?induced by thiazole-Zn. First, the?effects?of different thiazole-Zn doses and exposure times on the?thyroid?weights,?thyroid?morphology and serum hormone levels of?rats?were investigated. The results showed that thiazole-Zn increased?thyroid?weights and serum?thyroid-stimulating hormone (TSH) levels and induced?thyroid?cell?hypertrophy?and?hyperplasia?in a dose-related and time-related manner. Furthermore, measurement of?thyroid?radioiodine uptake in vivo in?rats?confirmed that thiazole-Zn inhibited active iodide uptake into the?thyroid, which reduced circulating levels of serum T3 and T4. Decreases in circulating THs resulted in a compensatory increase in serum TSH levels through a negative feedback system. Subsequently, sustained excessive stimulation of the?thyroid?gland by TSH led to?thyroid?follicular?cellhypertrophy?and?hyperplasia. In addition, thiazole-Zn increased sodium/iodide symporter (NIS) expression in the rat?thyroid, and the increased NIS expression promoted and restored iodide uptake into the thyroids of?rats. The risk of iodine intake inhibition by thiazole-Zn to humans, especially susceptible individuals, such as children and pregnant women, warrants additional attention.