This paper includes informations about nodulation capacity of 100 native species of the legume family from the states of Amazonas, Pará, Rondônia and Roraima (Brasil), evaluated in their original habitats and/or in nursery plots. Field observations were made in "terra-firme" forests, várzea, campinarana, savana, igapó, secondary forest, etc. Plant material was collected in a total of 11 habitats. The species were studied in nursery beds using soils from diferent regions. The genera and species of plants were identified at the INPA herbarium. The survey verified that 63% of the species presented nodules. These characteristics were observed in acid soils with different textures and fertility levels, with a pH varying from 3.9 to 5.9. Nodulation was more frequent in species of the sub-families Mimosoideae and Faboideae, than in Caesalpinioideae. The nodules collected had a great variability in color and shape, being more common coral shapes and creamy color. Data for nodulation of 21 legume species included 2 new genera not reported before: Acosmium (Faboideae) and Zollemia (Caesalpinioideae). Eleven species, which were tested for the first time, did not show nodulation. Habitat, type of plant growth, soil texture and low fertility had no effect on nodulation, which is considered to be related with other factors like properties inherent to the species and occurrence of compatible rhizobium strains in the different sites.