Abstract: Objective: To evaluate expression of CA-9, CD1a, CD3 and EGFR in Stage I non-small cell lung cancer (NSCLC) and to analyze the clinical and prognostic significance. Methods:Expression of CA -9, CD1a, CD3 and EGFR was measured in 59 stage I NSCLCs by immunohistochemistry. The extent of tumor necrosis was also analyzed. Results: CD1a, CD3 and EGFR expression was higher in adenocarcinoma than in squamous carcinoma (P<0.05). CD1a infiltration was lower in patients with positive CA-9 expression and with extensive tumor necrosis (P<0.05). The patients with extensive tumor necrosis had shorter overall survival than those with minimal necrosis (P<0.05). There was no difference in survival between patients who received chemotherapy and those whodid not. Further analysis indicated the overall survival of patients who received chemotherapy was shorter than that found in patients who did not receive chemotherapy if the tumors were positive for CA-9 expression (P<0.05) and negative for CD1a infiltration (P<0.05). Conclusion: Infiltration of CD1a +DCs and CD3 +T lymphocytes can be observed in early stage NSCLCs. Tumor hypoxia,histopathology and the extent of tumor necrosis may affect this infiltration. The extent of tumor necrosiswas strongly correlated with overall survival. The expression of CA-9 and CD1a may be used to helpclinicians decide the best course of treatment, especially in terms of chemotherapy.