Recent epidemiological studies on the effect of beta-carotene and/or other carotenoid (s) on cancer chemoprevention were reviewed and compared. Case-control studies and cohort studies sometimes did not provide consistent results. Studies on intake of beta-carotene and/or other carotenoid (s) and studies on their blood concentration often did not provide consistent results, either. Two major intervention studies on lung cancer in high-risk subjects indicated fed beta-carotene to possibly even enhance the risk of cancer. As a whole, beta-carotene and other carotenoids could not be unequivocally shown to qualify as agents for chemoprevention. For an epidemiological assessment of any chemoprevention potential of beta-carotene or other carotenoid (s) against cancer, the proper methods must be conducted on suitable human subjects. To do such an adequate epidemiological assessment, more detailed knowledge should be obtained beforehand by experiments.