OBJECTIVES: Despite frequently causing serious illness in adolescents, immunization programmes against pertussis have been restricted to children <7. We estimated the economic impact of introducing a booster dose of acellular pertussis vaccine in four Canadian provinces (Manitoba, Ontario, Québec, and Saskatchewan) using different vaccination schedules. METHODS: We conducted a cost-effectiveness analysis using a predictive spreadsheet model with adolescent’s aged 12 (cohorts of 17,400; 144,000; 88,000; and 16,000) over a 10-year horizon, from provincial Ministry of Health (MoH) and societal perspectives. For Québec, costs and benefits of adding acellular pertussis to combined diphtheria-tetanus vaccine (DacPT) in schools were compared to the current practice [diphtheria-tetanus vaccine (DT) only]. In Ontario, we assumed the new vaccine would be administered in school, compared to DT in physicians’ offices. In Manitoba and Sakatchewan, all vaccinations would be done in school, compared to 80%-90% presently. Efficacy and utilization data (vaccination, managing pertussis infection and hospitalization) were derived from the literature. Productivity loss of parents and older adolescents was estimated. Standard cost lists were used (CAD$), discounted at 3%. RESULTS: MoH perspective: the expected additional cost of DacPT/adolescent >10 years ranged from $3.98 (Ontario) to $10.57 (Québec); incremental cost-effectiveness ratios ranged from $127-$337/case avoided. Societal perspective: 10-year results ranged from $6.66 savings to an incremental cost of $7.47/adolescent. Manitoba and Saskatchewan results fell between those of Ontario and Québec. CONCLUSION: This study suggests that administering a booster dose of DacPT at age 12 may reduce the burden of pertussis at reasonable cost, potentially with savings to society. The impact of program implementation was lower in Ontario than other provinces, assuming additional savings by shifting vaccine administration from physicians to schools.