Screening for lung cancer has remained controversial since the completion, more than two decades ago, of the three large randomized controlled trials, sponsored by the National Cancer Institute, which led to the recommendation against screening by major medical organizations. Details of the controversy are given, which include concerns about the study design, implementation, and analysis. New evidence about the potential benefit of screening with chest radiography that has emerged since the completion of those trials is reviewed, as well as the results of studies of CT screening for lung cancer.