BACKGROUND: Bacterial meningitis is a severe and feared disease. We have studied bacterial meningitis in children in S?r-Tr?ndelag county during a 20-year period from 1988 to 2008. MATERIAL AND METHODS: Medical records of children (in-patients) with spinal fluid findings or a clinical diagnosis of bacterial meningitis, at St. Olavs Hospital, were retrospectively reviewed. RESULTS: 112 cases of bacterial meningitis were registered in children below 16 years of age in S?r-Tr?ndelag county between 1988 and 2008. Children younger than 2 years had the highest occurrence, with a mean annual incidence of 42.3 per 100,000, whereas the incidence among children in the age group 2 to 16 was 5.7 per 100,000. We observed a decline in the occurrence from 19.1 per 100,000 in the period 1988 - 1991, to 6.9 per 100,000 in the period 2003 - 2006. 31 cases of Haemophilus influenzae type B, 26 cases of Neisseria meningitidis group B, 26 of Streptococcus pneumoniae and 19 cases with other pathogens were registered. The occurrence of H influenzae and N meningitidis have declined over the entire period, whereas S pneumoniae has increased. 6/112 children died (5.4 %) and 34 developed sequelae (30.4 %). In a multiple logistic regression analysis, the maximal value of C-reactive protein was associated with an increased risk of developing sequelae, adjusted for age and triggering microbe. INTERPRETATION: The incidence of bacterial meningitis among children in S?r-Tr?ndelag has decreased significantly over the last 20 years, and meningitis is now a rare disease. Bacterial meningitis is most common among children below the age of two, and is still associated with a substantial mortality and risk of long-term neurological sequalae.