Background. The French public health agency has launched in March 2019 a campaign focusing on the long-term alcohol-related harms and low-risk drinking guidelines, aiming to improve knowledge and in turn to reduce alcohol consumption. A longitudinal study showed its effectiveness on alcohol consumption at short term. Based on these results, a cost-benefit analysis was performed.Method. A decision-tree followed by a semi-Markov model with 13 health states was developed to compare the alcohol prevention campaign with no intervention in the 18-75 drinkers population. The reference analysis adopted a health care system perspective and was led over a 30-year period. The model included mean cost of the campaign and avoided costs due to alcohol-attributable morbidity and mortality. To assess the uncertainty around the results, a deterministic sensitivity analysis was conducted, along with 16 scenarios analyses.Results. The cost-benefit analysis estimated a return on investment of €7 for €1 spent for the campaign. All scenarios showed positive returns. From a societal perspective including the valuation of years of life lost due to premature death, return on investment was found to be nearly 3 times higher (€20).Conclusion. Well-designed alcohol prevention campaigns can not only modify attitudes and health-risk behaviors but also produce long-term financial savings for the health system. These results support the dissemination of efficient mass media campaigns to prevent alcohol consumption in the general population.