Lung cancer is in epidemic proportions throughout the world. It is imperative that a simple, accurate staging system be used to direct treatment and evaluate its effects on long-term survival. The staging system must be the basis for current and future research on the newer adjuvant treatments for lung cancer. It should be internationally accepted, enabling a worldwide effort to improve survival. The new AJCC staging system meets these requirements, with early international reports confirming its usefulness and validity. The diagnostic radiologist, often directs the pretreatment workup of these patients and should be familiar with this new system.