The incidence of meningococcal disease in Navarra and Spain is determined for the 1991-1997 period, with a detected density of incidence of 5.46 per 100,000 in the 1987-1991 period. In Navarra the incidence in the 1991-1997 period was of 3.26 per 100,000 inhabitants, of which 1.91 per 100,000 corresponded to serogroup B, 0.77 per 100,000 corresponded to serogroup C, and a rate of 0.57 per 100,000 were non-grouped. During the year 1997 (weeks 1 to 35) the accumulated incidence in the period of MD serogroup C was of 0.38 per 100,000 (2 cases), the Ratio of Rates Navarra/Spain was 0.21. Considering that the last case of MD occurred in week 8, in an adult woman of 39 years and nonexistence of serogroup A in Navarra, it can bi concluded that there is no justification for a strategy of mass or routine vaccination with respect to meningococcus C.