This review focuses on the clinical use of PET to evaluate solitary pulmonary nodule (SPN) and non-small cell lung cancer (NSCLC). When SPN or mass without calcification is found on chest X-ray or CT, PET is an effective modality to differentiate benign from malignant lesions. For initial staging of NSCLC, PET is useful, and proved to be cost-effective in several countries. is useful for detecting recurrence, restaging and evaluating residual tumor after curative therapy in NSCLC. For therapy response assessment, PET may be effective after chemotherapy or radiation therapy. PET is useful to predict pathological response after neoadjuvant therapy in NSCLC. For radiation therapy planning, PET may be helpful, but requires further investigations. PET/CT is better for evaluating NSCLC than conventional PET.