Positron emission tomography (PET) imaging using (18)F-2-deoxy-D-glucose, a D-glucose analog labeled with fluorine-18 (FDG-PET), is being evaluated in the assessment of prognosis and therapeutic response in patients with non-small cell lung cancer. FDG-PET imaging has the potential to allow more appropriate selection of patients for surgical resection and for neoadjuvant and aduvant chemotherapy as well as chemoradiation. Currently, the absence of standardization in how FDG-PET images are obtained and interpreted limits its widespread clinical utility. Although prospective multi-institutional trials and standardization of FDG-PET imaging protocols are required for the true utility to be determined, the evolving experience with FDG-PET imaging indicates a greater and integral role in treatment decisions. This article will discuss the assessment of prognosis and treatment response in patients with non-small cell lung cancer using FDG-PET, and will emphasize potential advantages and limitations in clinical management.