INTRODUCTION The history of lung cancer epidemiology parallels the history of modern chronic disease epidemiology. Although an excess of lung cancer was first observed among miners and some other occupational groups in the 19th century, an epidemic increase in lung cancer began in the first half of the 20th century, with much speculation and controversy about its possible environmental causes. Later, lung cancer became a milestone in epidemiology when its predominant cause, tobacco smoking, was established in a series of landmark studies beginning in 1950. This chapter on the epidemiology of lung cancer will discuss the recent trends in lung cancer incidence and briefl y review the current topics that have been widely discussed at meetings and in the literature: Lung cancer in never-smokers, gender differences in the incidence of lung cancer, whether screening with low-dose computed tomography (CT) should be recommended, and the small but important improvements in survival among lung cancer patients. We also will present a summary of known risk factors of lung cancer.