The occurrence of sequelae 3-15 years after meningococcal disease has been investigated in a study on 71 patients and 64 controls. The patients were young men, aged 18 to 24 years at the time the disease was contracted. Participants filled in a questionnaire on possible symptoms. Audiometry and EEG were also carried out. The response rates were 84% among patients and 75% among controls. We found that 61% of the patients had one or more symptoms of possible sequelae compared to 20% in the control group (p less than 0.001). The symptoms were generally light and of mental or neurological type. Among the patients 13% stated that they had obvious complaints commonly attributed to meningococcal disease, compared to 2% only in the controls (p less than 0.05). Twenty-nine per cent of the patients stated that the disease had affected their education or working capacity. No statistical differences between patients and controls were demonstrated by audiological or EEG examinations. In only one single ear could deafness unequivocally be attributed to the disease.