The aim of the study was to determine whether patients with meningococcal disease carry meningococci in the throat both before and after treatment for the disease. During the 7 months of the study 106 patients with confirmed meningococcal disease were admitted to Danish hospitals, of whom 77 (73%) had a throat swab examined at least once and were included in the study. Sixty-two patients were examined on admission and 52 were examined on discharge; 37 were examined on both occasions. On admission, meningococci were isolated from 18 (49%) of 37 throat specimens examined selectively for pathogenic Neisseria spp. Meningococci were not isolated from any throat specimen taken on discharge from hospital; 47 (90%) of 52 of these specimens had been examined adequately. From an observed carriage rate of 0 out of 47 it can be judged that the carrier rate does not exceed 6.4% (95% confidence limit). From these results we conclude that it is unlikely that patients who have been treated for meningococcal disease according to the regimens used in Denmark can be the source of infection for secondary cases.