A Phase III malaria prevention trial was conducted in two camps of Liberian refugees in Sierra Leone using Insecticide Treated Polyethylene Sheeting (ITPS) or untreated polyethylene sheeting (UPS) randomly deployed to defined sectors of each camp. The ITPS was impregnated with pyrethroid insecticide during manufacture. In Largo camp the ITPS or UPS was attached to inner walls and ceilings of shelters, while in Tobanda the ITPS or UPS was used to line the ceiling and roof only. Cohorts of children up to 3 years of age were cleared of malaria parasites and monitored for up to 8 months post construction for possible malaria re-infection. Installation teams and refugee groups were blinded as to whether the sheeting was insecticide treated or not.