In a cross-sectional study of behaviour disorders amongst children attending three primary schools in Lusaka 210 children, aged 8-12 years, were assessed by means of the behaviour rating questionnaire developed by Rutter for teachers. The frequency of behaviour disorder was 14.8 per cent with sex ratio 1.9:1 (boy:girl). Children's mothers were interviewed to obtain background social and demographic information about the family, and anthropometric measurements were made on the children. Behaviour disorder was largely associated with characteristics of the school, socio-economic status, mother's occupation, play facilities at home and past history of hospitalization. The relevance of the behaviour rating questionnaire for developing countries is discussed.