Transesophageal, endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) and positron emission tomography (PET) scanning are new modalities for staging non-small cell lung cancer (NSCLC), the roles of which are still being defined. A 78-year-old man with a right lower lobe (RLL) mass and mediastinal adenopathy seen on CT scan had a PET scan that revealed only a RLL hypermetabolic area. EUS/FNA cytology of a subcarinal lymph node (LN) revealed the presence of NSCLC. This is a case of a false-negative PET scan for nodal involvement in NSCLC that was diagnosed with EUS/FNA. Patients with NSCLC and suspicious lymphadenopathy may benefit from EUS/FNA of enlarged posterior mediastinal LNs, even with negative findings of PET scanning.