Abstract: Objective:To investigate the effects of oyster peptide on the hypothalamus-pituitary-thyroid axis in kidney yang deficiency rats. Methods:Establish kidney-yang deficiency rat model by intramuscular injection of hydrocortisone for 35 days. At the end of experiment,detect some parameters including the serum free triiodothyronine(T3),serum free tetraiodothyronine(T4),serum thyrotropin(TSH),hypothalamic thyrotropin releasing hormone(TRH)mRNA expression and thyroid pathological changes on oyster peptide gavage group(300,150 and 75 mg/kg). Results:Compared with the normal control group,the T3,T4,and TRH mRNA levels of the model group were significantly lower(p<0.01),and the TSH contents increased significantly(p<0.01). In addition,unclear follicles and inflammatory cell infiltration were found in thyroid of model animals. Compared with the model group,oyster peptide gavage group(300 and 150 mg/kg)obviously improved T3,T4,TSH and TRH mRNA levels(p<0.05)and tend to normal level. 300 mg/kg oyster peptide gavage significant ameliorated thyroid lesions moreover. Conclusion:For kidney yang deficiency rats,oyster peptide could improve serum hormone levels and expression of TRH mRNA,and regulate hypothalamic-pituitary-thyroid axis in rats with kidney-yang deficiency.