The Amami rabbit Pentalagus [urnessi is an endemic species of the central Ryukyus, Japan, and occurs only on two islands, Amami Oshima I. and Tokunoshima I. For the conservation of this species, some research programs to reveal the population size, spatial and temporal patterns of activity, and impacts of introduced predators were carried out. The habitat available to the rabbit has obviously been reducing with considerable fragmentation on each island, and size of each population also seems to have been decreasing as well (2700-6500 in total of the two islands in 1995). The estimated home range size was relatively small (1.3 ha for males and 1.2 ha for females), and the rabbits moved 100-200 m from their burrows mainly during the night. The negative impact of the introduced mongoose on the rabbit was quite serious on Amami Oshima I., and effective control of this exotic predator is an urgent necessity for the conservation of the rabbit, as well as the whole ecosystem, of this island.