OBJECTIVE To investigate the significance of expression of p53, Mdm2 and p21WAF/ CIP1 proteins and their relationships. METHODS Pathological specimens from thyroid carcinoma, adjacent non-tumor thyroid tissues and thyroid benign lesions were examined for p53, Mdm2 and p21WAF/CIP1 proteins by tissue microarray technique and immunohistochemistry method. RESULTS The positive expression rate of p53, Mdm2 and p21WAF/CIP1 in thyroid carcinoma was 50.6 %(37/73), 63.0 %(47/73) and 38.4 %(28/73) respectively. The expression of p53 and Mdm2 increased(P