Objective:To investigate the HSP70 and TNF-α levels in thyroid cancer tissues and its relationship with clinicopathological characteristics of patients. Methods:We used RT-PCR and Western blot to detect HSP70 and TNF-α expression in 40 cases of thyroid cancer,20 cases of benign thyroid lesions and 15 cases of normal thyroid tissue and analyzed the relationship between HSP70 gene expression level and thyroid carcinoma pathological features. Results:The differences of the HSP70 mRNA levels among three groups were statistically significant(P < 0.001),and the HSP70 mRNA levels in thyroid carcinomas were significantly higher than that in normal thyroid tissue and benign thyroid lesions(P < 0.05);The HSP70 protein levels in thyroid carcinoma were significantly higher than that in normal thyroid tissue(P < 0.05);HSP70 mRNA expression level was significantly correlated with the thyroid cancer histological grade(rs = 0.810,P < 0.05);The differences of TNF-α mRNA level among three groups were significant(P < 0.05),and further study showed that thyroid carcinoma TNF-α mRNA levels were significantly higher than that in normal thyroid tissue as well as benign thyroid lesions (P < 0.05). Conclusion:Both HSP70 and TNF-α expression were increased in the thyroid carcinoma tissues,and the level of HSP70 expression was correlated with the thyroid cancer histological grade,suggesting that HSP70 plays a critical role in the thyroid cancer developing.