ObjectiveTo report on the haemoglobin concentrations and prevalence of anaemia in schoolchildren in eight countries in Africa and Asia.DesignBlood samples were collected during surveys of the health of schoolchildren as a part of programmes to develop school-based health services.SettingRural schools in Ghana, Indonesia, Kenya, Malawi, Mali, Mozambique, Tanzania and Vietnam.SubjectsNearly 14 000 children enrolled in basic education in three age ranges (7–11 years, 12–14 years and Ä15 years) which reflect the new UNICEF/WHO thresholds to define anaemia.ResultsAnaemia was found to be a severe public health problem (defined as >40% anaemic) in five African countries for children aged 7–11 years and in four of the same countries for children aged 12–14 years. Anaemia was not a public health problem in the children studied in the two Asian countries. More boys than girls were anaemic, and children who enrolled late in school were more likely to be anaemic than children who enrolled closer to the correct age. The implications of the four new thresholds defining anaemia for school-age children are examined.ConclusionsAnaemia is a significant problem in schoolchildren in sub-Saharan Africa. School-based health services which provide treatments for simple conditions that cause blood loss, such as worms, followed by multiple micronutrient supplements including iron, have the potential to provide relief from a large burden of anaemia.