The application discloses method of immunising against Neisseria meningitidis infection comprising the steps of a) immunising a human patient at a first age of between 0 and 11 months with a bacterial saccharide conjugate vaccine comprising at least one, two or three bacterial saccharide(s) separately conjugated to a carrier protein to form at least one, two or three bacterial saccharide conjugate(s); and b) immunising the human patient at a second age of between 12 and 24 months with a Neisseria meningitidis conjugate vaccine comprising at least two capsular saccharides selected from the group consisting of N. meningitidis serogroup A capsular saccharide (MenA), N. meningitidis serogroup C capsular saccharide (MenC), N. meningitidis serogroup W135 capsular saccharide (MenW135), and N. meningitidis serogroup Y capsular saccharide (MenY) conjugated separately to a carrier protein, wherein the Neisseria meningitidis conjugate vaccine is co-administered with a vaccine comprising diphtheria toxoid and tetanus toxoid.