The prognosis of lung cancer patients mostly depends on the stage at which the disease is diagnosed. Contrast-enhanced CT (ceCT) and MRI play a significant role in initial staging, but often the morphological information is insufficient when compared to the metabolic or molecular information obtained by positron emission tomography (PET). [18]F-fluorine deoxyglucose (FDG) is based upon the increased demand of ATP leading to increased consumption of glucose in the tumor tissues. FDG-PET/CT has been proven to be of immense value in the initial diagnosis, evaluation of therapy reponse, detection of recurrent tumor, radiation therapy planning and in the multidisciplinary management of patients with non-small cell lung cancer as well as in patients with small cell lung cancer. The aim of this article is to present a concise summary of the present status of FDG-PET/CT.