AbstractBackground:Smoking and exposure to environmental tobacco smoke are inadvisable for adults with asthma.Aims:To determine the smoking prevalence and daily smoking rate of asthmatics and compare smoking‐related beliefs and behaviours among smokers with and without asthma. To compare beliefs of asthmatics about passive smoking and asthma, how many are exposed at home and what they do when they are exposed, with people who do not have asthma.Methods:A representative population survey of 3019 South Australian adults aged 15 years and older interviewed in their own homes in late 11992.Results:Twenty‐eight per cent of asthmatics were smokers; mean daily smoking rate was 17.6. Asthmatics had similar patterns of smoking, readiness to quit and quit attempt histories as people without asthma. More than 40% of smokers with asthma did not perceive that smoking had greatly affected their health, over half did not believe they were at risk in future and two‐thirds did not think future health problems would be serious. Among non‐smokers, despite being more convinced of the effects of passive smoking on asthma, and being more concerned about exposure, those with asthma were no more likely to take protective action in response to actual or imminent exposure than those without asthma. One in ten non‐smokers with asthma were exposed to smoking at home.Conclusions:The smoking habits of adults with asthma are cause for concern, with many asthmatic smokers perceiving they are not personally at risk from their smoking. Health education principles should be used by health professionals caring for asthmatic smokers to guide the selection and delivery of smoking cessation strategies. Prevailing restrictions on indoor smoking play an important role in protecting the respiratory health of non‐smokers