Background. Casino workers are exposed to high levels of secondhand smoke (SHS) at work, yet remain at risk of being excluded from smoke-free legislation around the world. If the prime motivation for smoke-free legislation is the protection of workers, then a workforce experiencing ill-health associated with SHS exposure should not be excluded from legislation. This study aimed to determine the prevalence of respiratory and sensory irritation symptoms among a sample of casino workers, to identify any association between the reporting of symptoms and exposure to SHS at work, and to compare the prevalence of symptoms with that in other workers exposed to SHS. Methods. A postal questionnaire survey of 1568 casino workers in London. Using multivariate analysis we identified predictors of respiratory and sensory irritation symptoms. Results. 559 workers responded to the questionnaire (response of 36%). 91% of casino workers reported the presence of one or more sensory irritation symptoms in the previous four weeks, while the figure was 84% for respiratory symptoms. The presence of one or more sensory irritation symptoms was most strongly associated with reporting the highest exposure to SHS at work (OR 3.26; 1.72, 6.16). This was also true for reporting the presence of one or more respiratory irritation symptoms (OR 2.24; 1.34, 3.74). Prevalence of irritation symptoms in the casino workers was in general appreciably higher than that reported in studies of bar workers. Conclusion. Our research supports the need for comprehensive smoke-free legislation around the world, covering all indoor workplaces including casinos. © 2007 Pilkington et al; licensee BioMed Central Ltd.