The Waimiri Atroari are a Carib-speaking tribe of Amazonian Indians, whose population has declined since intensive contact with the outside world commenced in the 1970s. This is a study of their ethnobotany, with quantitative data for their use of the 214 tree and liana species in one hectare of terra firme forest. Seven principal plant use categories are discussed: food, technology, medicine, construction, fuel, ritual and commerce; and plant-use data are presented for over 300 species, together with information regarding their distribution and ecology.