The increased knowledge about the molecular mechanisms leading to the development of a tumor has opened new horizons for basic and applied research. Lung cancer is among the tumor entities with the highest incidence and mortality rates. Recently new drugs and therapeutic options for patients with lung cancer were developed. These developments demand new and improved techniques for the sensitive and specific detection of lung tumor cells. Some of the molecular genetic features of lung tumor cells are summarized and the possibilities to use these characteristics as new tumor markers are discussed.