Data from epidemiological and preclinical studies support the exploration of retinoids as preventative or therapeutic agents to combat lung cancer. To date though, retinoids or carotenoids have failed to reverse bronchial premalignant lesions or to reduce the incidence of lung cancer. Two large trials have actually demonstrated that beta carotene administration produces an increase in lung cancer incidence. Studies in patients with established disease have also been negative. These results have left researchers looking for new insights into retinoid action. Recent discoveries have provided new information concerning the molecular mechanisms by which retinoids are involved in the development of lung cancer and the role they play in maintaining a healthy bronchial epithelium. The search for more active retinoids continues; however it is unlikely that retinoids will have a significant impact effect when used as single agents. It is expected that more scientifically based trials of retinoids in combination will eventually produce advances.