Attempts to understand the relationship malaria transmission intensity and antimalarial drug resistance had rested mainly on mathematical models. To date, except for two studies which reported reductions in the prevalence of drug resistance in Tanzania and Zimbabwe, no other field data addressed the impact of reducing malaria transmission by the use of vector control measures on antimalarial drug resistance. Thus whether vector control decrease or increase drug resistance remains a contentious issue. The aim of this study was to investigate the impact of insecticide-treated curtains (ITCs) on clinical and parasitological outcomes in children with uncomplicated malaria treated with chloroquine (CQ), on the prevalence of genetic markers of resistance to CQ and sulphadoxine-pyrimethamine (SP) and on the ability of children to clear drug resistant parasites. The therapeutic efficacy of CQ was studied in 9 villages which used ITCs for 6-8 years and 9 villages with no history of ITC use. A cross-sectional survey was also conducted to estimate the prevalence of genetic markers of resistance to CQ and SP in asymptomatic children.