Sources of readily available data for cancer surveillance are frequently sought. To assess the validity of information on cancer risk factors that is routinely collected in conjunction with cancer incidence reporting, the authors completed interviews for 441 patients identified through the Missouri Cancer Registry from June 1986 to May 1987. Interviews elicited information on employment history, smoking, and alcohol consumption. Data collected from interviews were compared with those previously reported to the Registry by participating hospitals. Exact agreements of three-digit US Census codes were 70% for occupation and 72% for industry. Concordance for never- versus ever-smoking status was 83%, and a high correlation (r = 0.93) was observed for level of smoking. Agreement on alcohol consumption was lower (65%), largely because of the presence of false negatives. Misclassification occurred in a random manner for occupational variables; however, differential misclassification was present for smoking and alcohol histories. Despite the limitations of registry-collected data, these findings suggest that cancer registries that obtain information on cancer risk factors may be suitable for exploratory studies, especially those involving occupational cancer surveillance.