Bacterial meningitis continues to be a life-threatening disease and an important cause of severe disability in otherwise healthy individuals. This article reviews the aspects related to the prevention of secondary cases. Our understanding about the factors leading to an epidemic and the identification of high risk groups remains limited. For this reason, chemoprophylaxis can be used only for the prevention of secondary cases once an index case has been identified. The objectives of prophylaxis are threefold: (i) to eliminate nasopharyngeal carriage in household contacts; (ii) to prevent contacts from acquiring the disease and (iii) to treat infection in those incubating the disease. Chemoprophylaxis can only achieve the first of these objectives. Nasopharyngeal carriage of meningococci and Haemophilus influenzae can be eradicated with the use of antibiotics and their advantages and disadvantages are discussed. Prophylaxis should be given to household members and kissing and saliva-exchanging contacts of a case of meningococcal meningitis. The decision to give prophylaxis to extended family contacts, close neighbour contacts or children attending day-care centres where a case has occurred is controversial. It does not alter the course of an epidemic and close contacts are liable to become reinfected soon after prophylaxis. Prophylaxis of H. influenzae should be given to households in which there is at least one child (other than the index case) under 48 months of age. There is no agreement on the need to provide chemoprophylaxis to children in day-care centres because the risk of secondary infections is uncertain. An alternative to chemoprophylaxis is protective chemotherapy which can prevent the development of meningitis in individuals incubating the disease.