Smoking cessation has been called the 'gold standard' of healthcare cost effectiveness, producing additional years of life at costs that are well below those estimated for a wide range of healthcare interventions. However, the most effective approaches to smoking cessation are not the most cost effective. As we move from the least resource-intensive interventions (e.g distribution of self-help cessation guides) to those that are most resource-intensive (e.g. medical treatments, including the use of nicotine replacement products), both cost and effectiveness increase, but cost increases more rapidly. Nevertheless, it must be considered that different interventions are effective for different people. Resource-intensive treatments may actually be far more cost effective for many people who may not respond to less-intensive interventions. A considered review of the evidence recommends support of all of the major forms of smoking-cessation intervention; even the most expensive are highly cost effective compared with the majority of medical practices that have been studied. Despite their cost effectiveness, smoking-cessation services are not covered by many healthcare providers. This review concludes that such coverage is warranted, primarily because much less cost-effective secondary and tertiary care is covered, encouraging its utilisation, rather than primary prevention. However, the argument favouring coverage is not as clear-cut as might be assumed. Coverage of smoking cessation amounts to a direct subsidy for smokers who want to quit. It is not health 'insurance' in the theoretical meaning of the term. The distinction is important as healthcare systems contemplate future coverage of a range of behaviour-related preventive interventions.