Children treated for acute leukaemia are at increased risk of infection with Streptococcus pneumoniae. The basis for this may include low levels of pneumococcal antibody but this has not been well studied. The authors measured serotype-specifi c pneumococcal IgG antibody concentrations in children treated for acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) ≥6 months after completion of standard-dose chemotherapy. Pneumococcal serotype-specifi c IgG antibody concentrations were low. None of the subjects had protective concentrations against all the heptavalentpneumococcal conjugate vaccine serotypes. There was no signifi cant difference in antibody concentrations between subjects with ALL and AML (p≥0.05). Children treated for ALL and AML generally have non-protective antibody concentrations against S pneumoniae . There is signifi cant morbidity associated with pneumococcal disease in this patient group and strategies for vaccination are required.