The white-bellied hummingbird (Elliotomyia chionogaster ) is a species of hummingbird in the family Trochilidae. It is found at forest edge, woodland, scrub and gardens in the Andes, ranging from northern Peru south through Bolivia to north-western Argentina. There are also lowland populations in Santa Cruz, Bolivia, and Mato Grosso, Brazil. It is generally fairly common.
This species was formerly placed in the genus Amazilia. A molecular phylogenetic study published in 2014 found that Amazilia was polyphyletic. In the revised classification to create monophyletic genera, the white-bellied hummingbird was placed in a new genus Elliotomyia.
Its upperparts are green and its underparts are white. Unlike other similar hummingbirds in its range (for example the green-and-white hummingbird), the basal half of the inner webs of the rectrices are white, but this is typically only visible from below.