This study aimed at evaluating protective effect of taurine on the down-regulated expressions of thyroid hormone receptor (TR) genes in brains of mice exposed to arsenic (As). The SPF mice were randomly divided into As exposure group, protective group, and control group. The As exposure group was administered with 4 ppm As(2)O(3) through drinking water for 60 days. The protective group was treated with both 4 ppm As(2)O(3) and 150 mg/kg taurine. The control group was given with drinking water alone. The gene expressions of TR in the mouse brains of the three groups were analyzed by real-time PCR. Their protein expressions were examined by Western blot and immunohistochemistry. Our results showed that the gene expression of TRβ, a very important regulator of Camk4 transcription, was down-regulated in cerebral and cerebellar tissues of mice exposed to As. The expression of TRβ1 protein in the cerebral or cerebellar tissue significantly decreased in the group exposed to As compared to the control group. However, the expressions of TRβ gene and TRβ1 protein were significantly rescued in the group coadministered with taurine as antioxidant. These results indicated that taurine may have the protective effect on the down-regulated expressions of TR in brains of mice exposed to As.