The health of schoolchildren in developing countries has received increasing attention over the last decade. Mortality among schoolchildren is generally lower than in any other age-group. There is however considerable disease-related morbidity among school-age children much of it attributable to parasitic infections (Savioli et al. 1992; Chan et al. 1994; Bundy and Guyatt 1996). This morbidity may have both immediate and long-term consequences on health growth and the benefit gained from education (Warren et al. 1993; World Bank 1993). The importance of schools promoting health is increasingly being recognized and several school-health programmes have been implemented in developing countries. Such programmes which are considered a very cost-effective way of improving the health status of those attending schools (World Bank 1993) have mainly been directed at controlling parasites such as schistosomes and intestinal helminths (Savioli et al. 1992; Bundy and Guyatt 1996; Anon. 1997a b; Magnussen et al. 1997 2001a b). The present study was on the school-based control of urinary schistosomiasis. (authors)