OBJECTIVE: Pneumococcical vaccine is an affective preventive intervention to prevent pneucoccical pneumonia. In this study, cost-effectiveness of pneumococcical vaccination (23 serotipes) strategies in individuals aged 5 or more years was assessed. METHODS: Cost-effectiveness was measured in terms of cost per life year gained (LYG), comparing net programme costs and effectiveness. The net programme cost was calculated from vaccinating costs, assuming 70% compliance, less reduced health costs from pneumococcical pneumonia achieved with the programme. Vaccination costs were calculated taking into account a cost of 11,51 Euros per vaccine. Costs and benefits were estimated for 1996 using a 5% discount rate. RESULTS: A cost-effectiveness ratio of €9.023,27 per LYG was obtained for the universal vaccination of the population. The cost-effectiveness ratio was €113.177,12 per LYG in individual aged 5-24 years, €19.482,51 per LYG in those aged 25-44 years, €7.122,80 per LYG in those aged 45-64 y <0 in those aged >64 years. In the age group of >64 years, disease costs reduced were higher than vaccination costs, with a savings/costs ratio of 1,58. Results of cost-effectiveness analysis were sensitive to the vaccine price, vaccine efficacy and the percentage of pneumonias caused by S. pneumoniae, being less sensitive to health costs from pneumococcical pneumonia, hospitalization rate in patients with a community acquired pneumonia and vaccination compliance. CONCLUSION: Results obtained in this study shows that pneumococcical vaccination should be a priority preventive intervention in individuals aged >64 and 45-64 years.