There has been no documented mosquito surveys carried out in East Timor since the work of Portuguese workers in the 1960's. The last was a Territory Health Service (THS) Medical Entomology Branch survey of Dili in September 1991 to assist the Indonesian government in controlling general mosquito problems of Dili. Following the referendum and subsequent humanitarian crisis in East Timor in September 1999 WHO requested THS to conduct a medical entomological survey of Dili.