OBJECTIVE: To investigate the expressions and clinicopathological characteristics of E 2F-1, c-myc and p14 ARF protein in the squamous carcinoma and adenocarcinoma of lung. METHODS: The expressions of E 2F-1, c-myc and p14 ARF protein of 71 cases of squamous cell carcinoma and adenocarcinoma of lung, and the related peritumoral lung tissues were detected by using immunohistochemical technique. RESULTS: The positive rates of E 2F-1 and c-myc protein expression were 83.1% (59/71) and 81.7% (58/71) in cancerous tissues, which were significantly higher than 8.5% (6/71) in peritumoral lung tissues (P<0.05). And the positive expression of p14 ARF protein in cancerous tissues (52.1%) was lower than which in the peritumoral tissues (74.6%, P<0.05). The expression rates of E 2F-1, c-myc and p14 ARF protein were no correlated with age, gender, tumor size, histological type, differentiation degree, lymphnode metastasis and TNM stage of patients (P>0.05). And there were significant correlation in any two of three indicators of E 2F-1, c-myc and p14 ARF protein expressions by correlation analysis (P<0.05). CONCLUSION: Abnormal expression of E 2F-1, c-myc and p14 ARF protein may play an important role in the tumorigenesis and progression for the squamous cell carcinoma and adenocarcinoma of lung.