In August 2015, the Food and Drug Administration (FDA) issued warning letters to cigarette manufacturers promoting brands as "natural" or "additive-free" because of concerns that such marketing claims might mislead consumers into believing that these brands are less dangerous to smoke than others. The current study examined consumer beliefs about the relative harms of "natural" cigarettes, and whether these beliefs influenced perceptions of advertising and purchase intentions when participants were shown an advertisement for American Spirit cigarettes. Data were collected using a web-based survey conducted in 2013 among 3,006 U.S.-based web panel members aged 15 to 65 years. Ratings of "natural" cigarette health risks (i.e., misperceptions) differed by sex, race, education, smoking status, and age. Controlling for perceived risks of other cigarette types, never smokers (B = -0.31, p < 0.001) and ever/former smokers (B = -0.15, p = 0.002) had significantly fewer misperceptions of "natural" cigarettes than current smokers. Current smoking (odds ratio [OR] = 17.8), believing the ad was truthful (OR = 1.18), and having more misperceptions about "natural" cigarette health risks (OR = 1.13) were independently associated with greater purchase intention. Consumers perceived cigarettes marketed as "natural" or "additive-free" as less harmful, and this influenced their perceptions of advertising claims and intention to purchase, controlling for other factors. These findings underscore Food and Drug Administration's recent warning letters.