The results of the first two years of implementation of a large scale trial of insecticide-treated curtains in Burkina Faso are summarised in this presentation. The trial was conducted in a highly malarious area and involved a population of slightly less than 100,000, distributed in 158 villages over an area of almost 1000 km2. A remarkable impact on entomological parameters (Anopheles density, sporozoite rate, entomological inoculation rate) was accompanied by a relatively modest reduction of parasitological indices (prevalence and density of Plasmodium falciparum). All-cause mortality in children 0.5 to 5 year old showed over two years a 15% decline. The authors believe that the wide surface of the protected zone and the almost total coverage achieved in the intervention villages were the major determinants of the observed reduction of transmission. A conclusive interpretation of the mortality results requires a further follow-up of the study population.