Carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), neuron-specific enolase (NSE), cytokeratin 19 fragment (CYFRA), and pro-gastrin-releasing peptide (proGRP) can be used as tumor markers for lung cancer. CEA is sensitive for adenocarcinoma, SCC and CYFRA for squamous cell carcinoma, and NSE and proGRP for small cell carcinoma. A tumor marker is generally used as a marker to monitor the clinical course. Serum levels of pro-GRP, reflect the disease course of patients with small cell lung cancer more accurately than NSE or CEA. Among the patients with clinical N0-1 non-small cell lung cancer high serum CEA levels, adenocarcinoma histology, and large tumor dimension were significant predictors of pathologic N2 disease. CEA played a new role in predicting metastasis to mediastinal lymph nodes A more effective treatment may enhance the value of tumor markers to predict relapse.