The Amphiatlantic genus Machaerium consists of shrubs, trees, and lianas occurring from sea level to 500–900 m (rarely 1700 m). The genus is known from Mexico southward to Brazil and Argentina, with one species (M. isadelphum) extending to Trinidad and Tobago, and another species (M. lunatum) to the west coast of Africa. Of the estimated 130 Machaerium species, eleven species and three varieties are known from Ecuador. Four of these thirteen taxa are widely distributed in Central and South America. The remaining nine taxa are distributed from Venezuela to Brazil, with one species, M. quinatum, reaching Argentina. Three species and three varieties are here presented as new records for Ecuador. General morphology, taxonomic treatments with keys to species, descriptions, illustrations, and maps of all Ecuadorian species are provided.