Anacardium has a primary center of diversity in Amazonia and a secondary center in the Planalto of Brazil. The authors recognize 10 species, one of which, A. fruiticosum, is described here as new, and another, A. occidentale, is the cashew of commerce. Data from several thousand herbarium sheets, extensive field work, SEM studies of pollen and leaves, and a review of the anatomical literature forms the basis for this modern revision. A cladistic analysis reveals that there are two clearly defined clades within Anacardium. The ecology and economic botany of all species is discussed.