We randomly assigned private practitioners (n = 393) to receiving, by mail, a box of "Smoker" stickers and a recommendation to label smokers' charts with these stickers, or to no intervention. Twenty percent of the physicians reported using the stickers and applying them on 43% of their smoking patients' charts. The intervention had no impact on physician reports of the proportion of smokers advised to quit smoking, but physicians who reported using the stickers stated that they advised more smokers to quit after the intervention (89%) than before (80%, P =.02). Thus, self-reports by physicians indicated that use of the stickers was associated with an increased proportion of smokers advised to quit. However, overall, the intervention did not modify physicians' behavior.