STUDY OBJECTIVES: To describe empiric research related to lung cancer prevention strategies, including chemoprevention aimed at reducing lung cancer incidence and various smoking avoidance and cessation interventions aimed at reducing smoking rates. DESIGN, SETTING, AND PARTICIPANTS: Systematic searches of MEDLINE, HealthStar, and Cochrane Library databases to July 2001 and print bibliographies. For chemoprevention studies, we considered only randomized controlled trials (RCTs) with lung cancer incidence as an end point. For studies of smoking avoidance or cessation, we selected systematic reviews and meta-analyses, and searched for individual RCTs only where high-quality and current reviews and meta-analyses were not available. MEASUREMENT AND RESULTS: Chemoprevention of lung cancer has been studied in five RCTs of primary prevention, no RCTs of secondary prevention, and five RCTs of tertiary prevention. None of these trials has shown evidence for efficacy of any agents tested, including retinol (vitamin A), beta-carotene, N-acetylcysteine, and selenium. There is a great deal of evidence about a wide variety of clinician-based and community-based efforts at smoking avoidance or cessation. Certain approaches have been shown to be effective (eg, mass media public education campaigns, direct restrictions on smoking, clinician-based approaches ranging from brief clinician advice to more in-depth sessions, and "life-skills training" in schools). Some approaches have intermediate or short-term effectiveness (ie, youth access restrictions and school-based interventions), and others have been shown to be ineffective (ie, acupuncture and provider education) or have been insufficiently studied (ie, provider feedback). CONCLUSIONS: There are no agents that have been proven to be effective for preventing lung cancer. Several clinician-based and community-based interventions show promise for reducing lung cancer incidence through smoking avoidance and prevention.