Little is known of the current incidence and mortality of meningitis in developing nations, especially in Latin America. We reviewed all cases of meningitis in an isolation-fever hospital in Salvador, Brazil, for the decade 1973-1982. Of all admissions, 6,751 (27%) were for meningitis; 4,100 (61%) of these cases were of definite or probable bacterial etiology. Children younger than 15 years accounted for 79% of cases, and 45% of cases were in children under 2 years. The overall case fatality rate was 33%, with 50% of these deaths occurring within 48 hours of hospitalization. Neisseria meningitidis was the etiologic agent in 32% of the cases, with a case fatality rate of 14%. Epidemics caused by N. meningitidis group C, then group A, in 1974-1978 accounted for 60% of the cases. Streptococcus pneumoniae caused 17% of cases, with a case fatality rate of 59%. Haemophilus influenzae type b, the most common cause of nonepidemic meningitis, caused 23% of all cases, with a case fatality rate of 38%. Enterobacteriaceae were the etiology in only 3.6% of patients, but the case fatality rate was 86%. Cultures were negative in 18% of cases with purulent cerebrospinal fluid. A total of 84% of H. influenzae, 40% of S. pneumoniae, 78% of Enterobacteriaceae, and 15% of N. meningitidis cases occurred in children less than 2 years of age. Case fatality rates were highest in this group. Vaccines protective for this age group are urgently needed.