In recent years many countries of the European Union (EU) have implemented comprehensive smoking bans to reduce exposure to tobacco smoke in public places and all indoor workplaces. Despite the intense public debate, research on the impact of smoking regulation on health, particularly within the workplace, is still very limited. In this paper, we use a Diff-in-Diff approach and comparable micro-data – for a large number of European countries – to evaluate the impact of national comprehensive smoking bans on both perceived workers' health and presence of respiratory problems within workplaces. Results show that the introduction of comprehensive smoking bans has a significant effect on workers' perceived health, particularly on the probability of exposure to smoke and fumes, also controlling for risk exposure. We also highlight some unintended effects of smoking bans in terms of mental distress, which counteract the positive impact on risk exposure and physical health. The impact across countries is shown to vary with the degree of strictness of the bans.