In this article we describe the decision making process used to choose the best alternative for bringing under control an epidemic of meningococcal C disease, which occurred in Galicia in 1996. In the decision making process, we used a methodology which consisted on the identification and definition of a problem, in order to identify alternative solutions and to select one, and finally implement and evaluate it. The health problem was detected studying the data obtained from a survey conducted following an outbreak of meningococcal C disease in february 1995 and from the active epidemiological surveillance system created thereafter. Because this was a new, complex and severe problem, with far-reaching social consequences, critical for our organization, and with long-term implications, and because it was considered important to take the decision as objectively as possible and to clearly explain it, the methodology chosen to solve the problem was a non-programmed, multicriteria making decision process, carried out by a working group using a criterion weighting approach. This working group was created within the General Directorate of Public Health, composed of specialist and of people responsible for the different areas involved. The working group put into practice the different steps of the methodology. The assessment criteria and their respective weights were: effect (efficacy measured by the number of cases we could have prevented if the alternatives were applied in the previous season) 40%; cost (in millions of pesetas) 15%; acceptability (acceptance of and response to each strategy from different groups: general population, health care professionals, other Administrations with competency in Public Health) 30%; and coherence (adherence to the currently accepted strategies for disease control in other countries)15%. When these criteria were applied to the ten alternatives considered, a score was obtained for each one of them. The highest scoring alternative corresponded to the massive vaccination of the total population of Galicia between 18 months and 19 years of age.