OBJECTIVE: To integrate information on cigarette companies' understanding and use of menthol as summarised in published research based on previously internal tobacco industry documents with results from large population-based surveys of tobacco use and other independent sources. DATA SOURCES: Papers published in this supplement of Tobacco Control, together with papers identified using PubMed searches. RESULTS: Tobacco companies shaped consumer perceptions of menthol cigarettes. Menthol is not just a flavouring agent. Cigarette companies use menthol's ability to mask irritation and provide sensory effects to make menthol cigarettes appeal to youth and health-concerned smokers, in part because menthol makes low-tar cigarettes more palatable. Consistent with targeted marketing, youths, women and African Americans disproportionately smoke menthols. There appear to be complex interactions with addictive effects of nicotine. The ubiquitous addition of menthol by tobacco companies to over 90% of all tobacco products, whether labelled 'menthol' or not, demonstrates that menthol is not simply a flavour or brand. Menthol imparts sensory characteristics to cigarettes and has a complex interaction with nicotine that affects smoking behaviour whether it is perceived or not, or whether cigarettes containing menthol are marketed as 'menthol' or not. Adding menthol increases fine particles in cigarette smoke, which have immediate adverse effects on the risk of heart attack. CONCLUSION: Information from industry documents, confirmed by independent scientific literature, consistently demonstrates that menthol increases population harm from smoking by increasing initiation and reducing cessation in some groups. Menthol facilitates and increases smoking, which causes disease and death.