The records of 476 infants and children with bacterial meningitis treated between 1979 and 1982 were reviewed. By the sixth hospital day 90% or more of children with pneumococcal or meningococcal infection compared with 72% of children with Haemophilus infection (P less than 0.001) were afebrile. The rates of prolonged fever for 10 days or more, persistent fever for 5 to 9 days and secondary fever were 13, 13 and 16%, respectively. The conditions associated with prolonged fever for 10 days or more were subdural effusion (27%), drug fever (23%) and concomitant arthritis or pneumonia (20%); 15% were of indeterminable cause. The principal conditions associated with persistent fever for 5 to 9 days were other foci of disease (17%), nosocomial infections (16%) and subdural effusion (14%); in 42% the cause was unknown. The conditions associated with secondary fever were nosocomial infections (27%) and subdural effusion (23%); 39% were of indeterminable cause. Neither the duration nor the patterns of fever correlated with neurologic abnormalities at discharge, including hearing deficit.