Objective: To estimate the cost effectiveness of a four year, multifaceted, community based research project shown previously to help women quit smoking. Design: A quasi-experimental matched control design. Setting: Two counties in Vermont and two in New Hampshire, USA. Subjects: Women aged 18-64 years. Methods: Costs were the grant related expenditures converted to 2002 US$. Survey results at the end of the intervention were used to estimate the numbers of never smokers, former smokers, light smokers, and heavy smokers in the intervention and comparison counties, and 1986 life tables for populations of US women categorised by smoking status to estimate the gain in life expectancy. Main outcome measures: Cost effectiveness ratios, as dollars per life-year saved, for the intervention only and for total grant costs (intervention, evaluation and indirect costs). Results: The cost effectiveness ratio for the intervention, in 2002 US$ per life-year saved, discounted at 3%, was $1156 (90% confidence interval (CI) $567 to '), and for the total grant, $4022 (90% CI $1973 to '). When discounted at 5%, these ratios were $1922 (90% CI $1024 to $15 647), and $6683 (90% CI $3555 to $54 422), respectively. Conclusion: The cost effectiveness ratios of this research project are economically attractive, and are comparable with other smoking cessation interventions for women. These observations should encourage further research and dissemination of community based interventions to reduce smoking.