The public is largely unaware of the lower global risk associated with snus compared with that of cigarettes, but little is known of perceptions of relative risks for specific diseases. Inveterate, daily, and nondaily smokers' perceptions of the relative snus/cigarette risk of cardiovascular disease, and of cancer of the lung, stomach, and oral cavity, and perceptions among smokers, snus users, and dual users of the relative risk of nicotine addiction, was studied in a pooled sample from annual national surveys (2008-2011) performed by Statistics Norway. The total sample included 2,661 ever smokers and snus users aged 15-79 years old. Fifty-three percent were men, and the average age was 46.1 year. Compared with medical consensus, all smoker groups overestimated the relative risks of diseases from snus use, and inveterate smokers overestimated them significantly more than other groups. For all diseases except lung cancer, the majority of smokers thought snus users were running a higher or equal risk. For lung cancer, 22% believed that snus use gave a higher or equal risk. Smokers, snus users, and dual users tended to think that snus and cigarettes were equally addictive products, while a somewhat higher proportion of those who had quit both products thought that cigarettes were more addictive. Increased knowledge of the relative health risks might give smokers an incitement to switch to snus and prompt current dual users to stop smoking completely. Awareness could be improved by tailoring information at targeted groups, for example via the health care system.