In the past 5 years, metabolic imaging with positron emission tomography (PET) using 18F-fluoro-2-deoxy-glucose (FDG) has become an important imaging modality in lung cancer patients. FDG-PET consistently proved to be superior to structure-based imaging modalities in both the diagnosis and staging of lung cancer. At this moment the use of FDG-PET in these indications needs further validation in multi-centre large-scale randomised studies, focusing mainly on treatment outcome parameters, survival and cost-efficacy. More recently, interesting findings have also been reported in the response assessment to cytotoxic treatments providing information of greater prognostic significance than can be obtained using conventional approaches. This review focuses on the potential role of FDG-PET in the diagnosis of lung nodules and masses, and in locoregional and extrathoracic staging of non-small cell lung cancer. Emphasis is put on the potential clinical implementation of the numerous data of the last decade.