To study complications and sequelae of serogroup B and C meningococcal disease, a retrospective survey examined the outcome of all culture-proven cases reported in the province of Quebec, Canada, from January 1990 through December 1994 (serogroup B, 167 cases; serogroup C, 304 cases). Data were collected from medical files, postal questionnaires, and telephone interviews. Age groups having the most cases were the 10-19-year age group for serogroup C and the <1-year age group for serogroup B. Fatality rates were 7% for serogroup B and 14% for serogroup C disease. Only 3% of survivors of serogroup B disease had physical sequelae, compared with 15% of survivors of serogroup C disease (skin scars, 12%; amputations, 5%; hearing loss, 2%; renal problems, 1%; and other sequelae, 4%). These results confirm the gravity of disease caused by serogroup C, serotype 2a Neisseria meningitidis and justify liberal use of vaccination for outbreak control.