The distribution of Formosan monkeys in Taiwan has been researched by the Macaque Research Group of Japan since 1967. In 1982, the Macaque Research Group of Japan conducted a questionnaire survey. From our past surveys, the answers to the questionnaire, and the 1982 survey, we were able to list 75 habitats of Formosan monkeys. The monkey population is more concentrated in southeast Taiwan than in other areas. This biased pattern of distribution may be attributed to the effect of forest destruction and regional development, rather than to the hunting activities by man. The density of monkey groups was estimated to be at least 0.1 group/km2. The range of the group of Formosan monkeys at Chihpen village, Taitung, was estimated to be about 2 km2. The size of this group is comparable to the average group size of Japanese monkeys.