BACKGROUND: Despite modem diagnostic, staging, and therapeutic advances, esp. with molecular biologic techniques, the 5-year survival rate of all cases of lung cancer does not exceed 15%. Also, the incidence of lung cancer of both sex in Korea is increasing year by year and the lung cancer is one of the leading causes of cancer death. Therefore, it is strongly needed to develop the new combination of treatment modalities including neoadjuvant chemotherapy and to identify tumor specific characteristics with staging or prognostic markers. Here we present the clinical significance of several biologic tumor markers to use as a prognostic markers in patients with non-small cell lung cancers. METHOD: The survival has correlated with the expressibility of proliferative cell nuclear antigen (PCNA), epidermal growth factor receptor(EGFR), p53 and/or blood group antigen A(BGAA) using immunohistochemistry in 46 patients with non-small cell lung cancers. RESULTS: 1) The expression rates of PCNA, EGFR, p53 and BGAA were 80.6%, 61.3%, 45.9% and 64.3%, respectively and those were not correlated to cell types or clinical stges. 2) The expression of BGAA was correlated with better survival in median survival and in 2-year survival rate and that of PCNA was correlated with worse survival in median survival and 2-year survival rate. 3) The expression of EGFR or p53 was not valuable to predict prognosis in non-small cell lung cancers. 4) With simultaneous applications of PCNA, EGFR and p53 immunostain, the patients with 2 or more negative expressions showed better prognosis than the patients with 2 or more positive expressions. CONCLUSION: It is suggested that the expression of blood group antigen may be a positive prognostic factor and that of PCNA may be a negative prognostic factor. Also, the combination of expressions of PCNA, EGFR and p53 may be used as a negative prognostic factor.