The epidemiology of Timor filariasis was observed during a clinical and parasitologic survey of persons living in a remote village on the island of Flores, Southeast Indonesia. Infection and disease was distributed evenly throughout the community, which was in accord with the breeding and feeding habits of the only identified vector, Anopheles barbirostris. Although micfofilaremia rates appeared independent of host variables of age and sexes and sex, symptoms of disease were greater among males than females, and in both sexes disease rates more than doubled between the first and second decades of life. Symptoms included recurring episodes of inguinal and femoral lymphadenitis with retrograde lymphangitis and fever, abscesses of lymph glands or vessels along the path of the great sapheneous vein and its mae highest yet reported for the Timor filaria; it is a virulent parasite causing serious ill-health among the inhabitants of eastern Flores.