Fluoro-deoxyglucose positron emission tomography (PET) imaging has a diagnostic and prognostic value in the initial staging, restaging, and surveillance of non–small-cell lung cancer (NSCLC). When used in conjunction with conventional radiologic imaging, PET imaging has been shown to result in significant changes in clinical management of NSCLC. Specifically, baseline PET imaging can improve initial staging and guide surgical and radiotherapy planning, whereas repeat PET imaging after the initiation of chemoradiotherapy can predict tumor response and help tailor therapy. After the end of definitive treatment, PET has greater diagnostic accuracy than other imaging modalities for the detection of tumor recurrence. The recent development of fused PET/CT imaging has improved the radiologic evaluation of NSCLC patients by combining metabolic and anatomic imaging; however, this has resulted in more complexity in the image interpretation. It is important for the interpreting physician to understand the role PET/CT plays in the staging, assessment of treatment, and follow-up after therapy in the multidisciplinary management of patients with NSCLC.