Objective:The aims of this study were to evaluate potential side effects of 18F-fluoroerythronitroimidazole (18F-FETNIM) as a new-type hypoxia-imaging agent and to investigate the feasibility of 18F-FETNIM PET imaging in advanced non-small cell lung cancer (NSCLC) patients and the correlations of hypoxia extent with tumor volume or pathological type. Methods: Twenty-six NSCLC patients were prospectively included in the study. PET/CT scans were performed 2 h after intravenous injection of 18F-FETNIM in all 26 patients. A pixel-by-pixel calculation of tumor to blood (T/B) activity ratio for all image planes was calculated. The number of pixels in the tumor volume with a T/B ratio≥ 1.5,indicating significant hypoxia,was determined and converted to mL units to measure the hypoxia volume (HV). Results: The images were clearly identified after 2 h post-injection of 18F-FETNIM. The tumors in 4 cases were not distinguished from background,while the remaining 22 displayed local 18F-FETNIM uptake in thoracic lesions moderately to markedly higher than background. There was no correlation between 18F-FETNIM uptake with pathological type. There were significant correlations of HV and also the T/B ratio with tumor volume. Conclusion:18F-FETNIM is a promising hypoxia-imaging agent which clinical use is safe and satisfactory. The preliminary study provides valuable methods and experience to its further research. Objective: The aims of this study were to evaluate potential side effects of 18F-fluoroerythronitroimidazole (18F-FETNIM) as a new-type hypoxia-imaging agent and to investigate the feasibility of 18F-FETNIM PET imaging in advanced non-small cell lung cancer (NSCLC) patients and the correlations of hypoxia extent with tumor volume or pathological type. Methods: Twenty-six NSCLC patients were prospectively included in the study. PET / CT scans were performed 2 h after intravenous injection of 18F-FETNIM in all 26 patients . A number of pixels in the tumor volume with a T / B ratio ≧ 1.5, indicating significant hypoxia, was determined and converted to mL units to measure the hypoxia volume (HV). Results: The images were clearly identified after 2 h post-injection of 18F-FETNIM. The tumors in 4 cases were not distinguished from background, while the remaining 22 displayed local 18F- FETNIM upt There was no correlation between 18F-FETNIM uptake with pathological type. There were significant correlations of HV and also the T / B ratio with tumor volume. Conclusion: 18F-FETNIM is a promising hypoxia -imaging agent which clinical use is safe and satisfactory. The preliminary study provides valuable methods and experience to its further research.