In order to study the causes of prolonged and secondary fever in bacterial meningitis, a group of 102 infants and children with proven bacterial meningitis were studied. The causative agent was Haemophilus influenzae in 58% of patients, Streptococcus pneumoniae in 25% and Neisseria meningitidis in 17%. Prolonged fever was observed in 12% of the patients. The established causes include, in order of frequency, subdural effusion, drug fever, otitis media, gastroenteritis and urinary tract infection. Secondary fever was noted in 18% of the patients. The causes, in order of frequency, were urinary tract infection, subdural effusion, otitis media, phlebitis, pneumonia and drug fever. Neither relapse of the meningitis nor inadequate response to antibiotic therapy was the cause for prolonged or secondary fever. Neurological sequalae were observed in 21 patients. There was no correlation between prolonged or secondary fever and neurological sequalae. We conclude that prolonged and secondary fever in patients with treated bacterial meningitis is rarely caused by the primary infection.