When investigating the specific immune response, the authors found that as many as 97.95% subjects in the investigated community had positive titres of anti A meningococcal antibodies. The values of geometrical means of anti A antibody titres varied between 16.85 and 20.25. Short-time carriers have substantially higher antibody levels than long-term carriers, the difference being statistically significant p less than 0.001. In the course of the investigation antibody levels rose despite the fact that meningococci of group A were not isolated. The position as regards anti C meningococcal antibodies is much worse. There the percentage of positivity is only 24.48% and the values of the geometrical means of titres in positive subjects varied between 7.78 and 8.48. On the whole group of subjects the values were, however, 2.09-2.42. This means they did not by far reach the value of the 1:6 titre, which is considered the first positive titre. Similarly as in anti A antibodies, there is a significant difference between the antibody level in short-term and long-term carriers in favour of the short-term ones.