Abstract: Objective :To investigate the expressions of cell cycle controlling genes,such as p27,CyclinD1,CDK4 and Rb in different types of thyroid tumorous tissues,in order to offer the data for carcinogenesis of the thyroid and information for clinical diagnosis. Methods :Flow cytometry and Immunofluorescence technique were used to perform the quantitative detection for the expression of p27,CyclinD1,CDK4 and Rb proteins in 40 cases with papillary carcinoma of the thyroid(PTC),16 with thyroid adenoma(TA),21 with nodular goiter(NG)and 10 with normal thyroid(NT). Results :The up-regulated expression of Cyclin D1,and CDK4 in PTC tissues was significantly higher than in other three groups(P<0.01),and no difference was found in NT,NG and TA tissues(P<0.05).The expression of p27 was down-regulated in NG,TA and PTC groups comparing to the NT group(P<0.05).There was no significant difference among PTC,TA and NG tissues(P<0.05).However,the difference between the expression of Rb and other four types of thyroid tumour tissues was not significant(P<0.05). Conclusion s:The over-expressions of CyclinD1 and CDK4 and the lower expression of p27 play important roles in carcinogenesis of PTC,whereas,Rb does little effect probably.