The Northern Territory has a history of various mosquito borne diseases, including malaria, dengue, Australian encephalitis and epidemic polyarthritis. Malaria transmission has been eradicated from the Northern Territory, but each year we have a number of imported cases from overseas malarious countries that make us vulnerable to its reintroduction. The vector of dengue has not been established in the Northern Territory for many years, and although there are occasional instances of imported insects, we are not receptive to this disease. It is still probable to be infected in the Northern Territory with the causative viruses of the other two diseases mentioned above. The Medical Entomology Branch of the Department of Health and Community Services has ongoing programs of mosquito monitoring, control and awareness throughout the Northern Territory to reduce the incidence of these diseases.