Leprosy (Hansen's Disease) is primarily a disease of the peripheral nerves and the skin, caused by the bacillus Mycobacterium leprae. It was introduced into the Northern Territory (NT) in the 1880's and spread to involve all Aboriginal groups of the Top End by the 1950's. Cases have also been found in Central Australia and in the migrant population. Active case finding and treatment has brought about a marked reduction in the incidence of leprosy over a fifty year period, with the overall incidence currently less than two cases per hundred thousand per year. As a result, widespread active case finding by the Leprosy/TB Control Unit is no longer a cost effective or practical option for leprosy control. However awareness by health staff of the signs and symptoms of leprosy, provision of clear diagnostic guidelines, education of the at risk groups, and provision for curative treatment, is needed to eliminate transmission of this disease.