Abstract: Objective : To investigate the expression of Matrix Metalloproteinase-9 mRNA(MMP-9m RNAJand Tissue Inhib ito rs of M etalloproteinase-1 mRNA (TIM P-1m RNA) and in different tissues and explore their correlation with metastasis and prognosis in thyroid tumor, to discuss the ir function in the invasion and metastsis of papillary thyroid carcinoma (PTC). Methods :Paraffin slices and in situ hybridization (ISH) were used to exam ine mRNA expression of MMP-9, TIMP-1 in 20 PTC,20 thyroid adenoma,20 nodular goiter and 20 normal thyroid tissue (harvest from sideward carcinoma). Results : MMP-9 mRNA positive expression was rem arkably strong in PTC (P<0.01), and rather weak in norm al thyroid tissue (P <0.01). There was significantly positive m odulating correlation between MMP-9 mRNA expression and PTC clinopathological factors (Tum or size, C linical stage, Lymphnode,prognostic index) (P<0.05 or P<0.01). For the case of TIM P-1mRNA, it showed positive expression in norm al thyroid tissue, benign thyroid nod and PTC. Among them, the expression of TIMP-1 m RNA was the strongest in PTC, and the weakest in norm al thyroid (P<0.05). While there was significantly negative modulating correlation between TIMP-1mRNA expression and PTC clinopathological factors (P <0.05 or P <0.01), that is, with the down -graduate of TIMP -1 m RNA, the PTC put up high malignant and bad prognostic. Conclusions : The expressions of MMP-9 mRNA and TIMP -1 mRNA have a close relation with the invasion and metastsis of PTC, and their overexpression can act as a standard reference to evaluate metastsis and unfavourable prognosis of PTC.