The systematics and biogeography of the neotropical angiosperm genus Tachia Aubl. (Gentianaceae: Helieae) were investigated. The genus includes 13 neotropical species from Guyana in the east to western Peru in the west and from Costa Rica in the north to central Bolivia in the south. Tachia grandifolia var. orientalis is raised to the species rank as Tachia orientalis. Illustrations, a diagnostic key, phenology, distribution maps, and descriptions are provided for all species.