Abstract: Objective 　To study the relationship between the expression of p53 and prolifera-ting cell nuclear antigen ( PCNA) in lung squamous cell carcinoma and clinicpathological features. Methods 　The expression of p53 and PCNA were detected in 36 cases of lung squamous cell carcinoma and 10 cases of normal lung tissues by SP immunohisto-chemistry. Results 　The positive rates of p53 and PCNA was 58. 3% (21/36) and 91.7 %(33/36) respectively. The positive rates of p53 and PCNA were correlated with histological grades, dimensions and lymph node metastasis. The differences were significant ( P < 0. 05) . The positive rates between p53 and PCNA were associated ( P < 0. 05) . Conclusion 　The detection of p53 and PCNA is valuable for evaluating the malignancy degree and lymph node metastasis of lung squamous cell carcinoma.