Lung cancer is a fairly common malignancy. An early diagnosis and a reliable staging and re-staging with the aim to detect both local and distant relapse are of utmost importance in planning the therapeutic management. The imaging diagnostic work-up of patients with lung cancer usually includes conventional imaging (chest X-ray, contrast-enhanced CT, bone scan) and more recently 18F-FDG PET/CT. Great advances in the management of lung cancer are based on the information provided by 18F-FDG PET/CT, as it supplies both metabolic and anatomic information (better localisation). There is vast evidence in the literature demonstrating its utility in (a) characterising benign versus. malignant solitary nodules, (b) staging and re-staging lung cancer, (c) guiding the type of therapy, (d) monitoring treatment response and (e) predicting outcome. In particular, given its specificity in differentiating 18F-FDG-avid relapse from post-surgical changes or post-radiation fibrosis (which do nott take up 18F-FDG), PET/CT can detect recurrent disease after initial treatment and (being a whole-body technique) and has demonstrated high accuracy in the detection of distant metastases or secondary tumours. In conclusion, 18F-FDG PET/CT can be considered a highly accurate and reliable method for staging and re-staging lung cancer, and is highly effective in guiding personalised therapies.