Correctly staging lung cancer is extremely important because treatment options and prognosis differ significantly by stage. In this review, the performance characteristics of positron emission tomography using F-18-fluoro-deoxyglucose (FDG PET) for staging the mediastinum are given in comparison with other non-invasive imaging modalities on the basis of current literature data. There are three meta-analyses demonstrating that FDG PET is more accurate than CT for detecting mediastinal metastases. First publications suggest that dual-modality PET-CT may provide a further gain in accuracy. Additionally, whole-body FDG PET provides information on M-staging and prognosis. Data comparing FDG PET with other functional imaging modalities or endoscopic ultrasound are limited. The necessity of a histological confirmation of PET results is still under discussion.