Lung cancer is the second leading cause of cancer in the United States and the leading cause of cancer-related death among men and women. Worldwide, lung cancer and lung cancer related deaths have been increasing in epidemic proportions, largely reflecting increased rates of smoking. In the year 2003, the American Cancer Society predicted that there would be approximately 171,900 new cases of lung cancer diagnosed and approximately 157,200 lung cancer-associated deaths in the United States. Worldwide, it is estimated that there were 1 million deaths in the year 2000. Cigarette smoking is the major risk factor for lung cancer, causing approximately 87% of lung, bronchial, and tracheal cancers. Other risk factors include family history, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, environmental radon exposure, passive smoking, asbestos exposure, and certain occupational exposures., In addition, for a given amount of tobacco exposure, some studies suggest that women are at higher risk than men. By far the most important public health intervention that could reduce lung cancer incidence and deaths is changing smoking habits. For many of these reasons, screening for and treating early lung cancer is intellectually appealing. However, there are several important methodological issues that must be critically analyzed before considering widespread screening. Screening for lung cancer is not currently recommended by any major medical professional organization. The United States Preventive Services Task Force (USPSTF) gave lung cancer screening a D. recommendation in both 1985 and 1996, meaning that there is fair quality data to recommend against screening for lung cancer. This recommendation was largely based on three negative United States trials conducted in the 1970s, 1 evaluating chest x-ray and 2 evaluating sputum cytologic screening. However, since the last Task Force review, several new studies of lung cancer screening have been reported, and greater attention has been directed toward the limitations of existing literature. This review examines studies of lung cancer screening to aid the current US Preventive Services Task Force in updating their recommendation.