Abstract: Objective: To study the relationship between the expression of p53,proliferating cell nuclear antigen(PCNA) and cell proliferaive activity of non-small cell lung carcinoma(NSCLC).Methods: The expression of p53,PNCA was studied in 60 cases of NSCLC by S-P immunohistochemical method.Results: The positive rate of p53 in NSCLC was 53.3%,which was higher than that in the per cancerous tissues(P<0.001 to P<0.05).There was positive correlation between p53 expression and lymph node metastasis,clinical stage and pathological grade(P<0.05 to P<0.005),but there was no statistically correlation between p53 expression and histological type(P>0.05).Conclusions: p53 protein,which may have some effects on genesis and development of tumor,relates to lymph node metastasis,clinical stage and degree of differentiation of NSCLC,and increases tumor cell proliferations.The examination of p53 protein has value great in the assessment of prognosis and diagnosis of lung cancer.