OBJECTIVES: To evaluate the cost-effectiveness of three different immunization strategies (1st: one time routine vaccination of all adolescents aged 11 years [yr], 2nd: college freshmen aged 18yr, and 3rd: college freshmen living in dormitories aged 18yr) with meningococcal polysaccharide (serogroups A, C, Y and W-135) vaccine [MCV4] compared to no vaccination from a societal perspective. METHODS: A decision analysis model using backward induction method was employed with parameter values from published literature and HCUPnet (Healthcare Cost and Utilization Project). All subjects were followed until they reached 29yr-old. Direct costs (vaccine, administration, hospitalization, outbreak control, and lifetime care) and indirect costs (patient and healthcare workers time cost) were measured in 2005 US$. Effectiveness was measured as quality adjusted life years [QALYs]. All costs and QALYs were discounted at 3% and cost-effectiveness was measured as incremental cost per QALYs gained [ICER]. Uncertainty was evaluated using multiple one-way sensitivity analyses. RESULTS: All strategies yielded favorable ICERs ($16746, $29447, and $19203 for 1st, 2nd, and 3rd strategy, respectively). The results were more favorable when herd immunity was considered ($9916, $18163, and $11402 for 1st, 2nd, and 3rd strategy, respectively). All strategies were highly sensitive to the duration of vaccine efficacy and the discount rate. A 50% decrease in these parameter values led to more than a 100% change in ICERs. The herd immunity effect of 25%, 50%, and 75% lead approximately to 25%, 40%, and 50% change in ICERs. The model was sensitive to the disease incidence rate, the risk for sequelae, and the vaccine cost, but not to direct costs for treatment and the vaccine efficacy. CONCLUSION: Three immunization strategies were cost-effective compared to no vaccination using a societal threshold cut-off of $50,000 per QALY. This analysis shows the opposite result to previous U.S. findings. Further research is needed to explain these discrepancies.