To evaluate the effects of cigarette advertising on brand switching, an accurate estimate of the extent of cigarette brand and company switching among current smokers is needed. Data from the 1986 Adult Use-of-Tobacco Survey were analyzed to estimate the percentage of adult smokers who switched cigarette brands and companies in the previous year. Approximately 9.2% of adult smokers (4.2 million) switched cigarette brands in 1986, and 6.7% (3.1 million) switched cigarette companies. The aggregate profitability of brand switching in 1986 was approximately $362 million. Based on this analysis, brand switching alone justifies only a small percentage of a cigarette company's advertising and promotion expenditures, suggesting that future research should address other potential effects of advertising, including maintenance of brand loyalty and expanding the cigarette market. Medical Subject Headings (MeSH): addictive behavior, advertising, smoking, tobacco.