OBJECTIVE: We conducted a cost-benefit analysis of two approaches to manage a regional outbreak of serogroup C meningococcal disease (MCD): 1. a planned mass immunization program (MIP) of 2,000,000 Quebec residents aged 2 months to 20 years, that would be implemented in September 2001; 2. an emergency MIP implemented at the peak of subsequent outbreaks. METHODS: As a reference case, we used the scenario that occurred in Quebec in 1991—several targeted regional vaccination programs were implemented in an attempt to ward off a more widespread outbreak of MCD. Unfortunately, at the end of 1992, public-health authorities had to implement a province-wide emergency MIP. We assessed the benefit of the programs using epidemiological data from the previous cycle of MCD in Quebec. Benefits included the number of new MCD cases prevented by the administration of Menjugate™ and their associated hospital and societal costs due to premature mortality and related morbidity. Costs included acquisition and administration cost of the conjugate vaccine, clerical, physician and health-services costs, and those related to lost productivity. We conducted the analysis in a societal perspective assuming Quebec would face a similar epidemiological situation in 2001as the one that started in 1991. All costs were transformed into 2001 Canadian dollars at an annual inflation rate of 3%. RESULTS: Over a 12-month period, a planned MIP would prevent 127 new cases (18 deaths, 24 major complications) while saving $15.0 million in direct costs to the Ministry of Health and $19.8 million in societal costs to the province of Quebec. CONCLUSION: As Quebec is facing a new epidemic cycle of MCD, the results of this analysis suggest that a planned MIP to be implemented in September 2001, would be cost-beneficial as opposed to delaying mass immunization until another outbreak occurs.