This data package makes available tree-by-tree diameter and floristic data from 91 samples of 0.1-ha each, in community and protected lands in eastern Madre de Dios, in Amazonian Peru. Data were collected by a team of Peruvian botanists and assistants, in a collaboration between the University of Leeds, the Universidad Nacional San Antonio Abad del Cusco, and the Instituto de Investigaciones de la Amazonia Peruana. This work was part of a project funded by the U.K. Department for International Development, and represents the first coordinated contribution to the international RAINFOR consortium (Red Amazónica de Inventarios Forestales). Fieldwork was conducted in 1998 and 1999, with subsequent herbarium work focused on accurate identification of the plants collected. The field protocol involved the locally randomised location of sample plots within culturally and biophysical strata as defined by Landsat imagery in conjunction with researcher knowledge and representatives of the local indigenous and immigrant rural communities. The primary contrast is between ‘altura’ and ‘bajio’ forest systems, the former being terra firme forests on largely Pleistocene deposits, the latter in the Holocene floodplain zone (some but not all sites experiencing occasional flooding). Each 0.1-ha sample is a modified Gentry plot, with non-scandent stems down to 2.5cm diameter measured and identified, at a height of 1.3m or above buttresses. For further details on methodology please see the references indicated.