Endotracheal metastasis of primary lung cancer is extremely rare. We report the case of a 51-year-old male patient who had undergone right pneumonectomy for squamous cell carcinoma one year earlier. The post-operative chest computed tomog-raphy (CT) image revealed a very small endotracheal nodule with contrast enhancement. This finding was erroneously regarded as endotracheal phlegm because of the nodular size and the rarity of endotracheal metastases from primary lung cancer. This case indicates that a thorough evaluation should be performed with a high level of suspicion for malignancy when a nodule-like lesion with contrast enhancement or tracheal thickening is detected on follow-up CT scan in patients who undergo surgery for lung cancer.