The White-bellied Antbird (Myrmeciza longipes), is a passerine bird which breeds in the tropical New World from Panama to northern Brazil and in Trinidad. It is also called Swainson's Antcatcher after William John Swainson.

This antbird, like others in its family, is a forest bird with a preference for undergrowth in dry or moist deciduous habitats. It is a resident breeder which lays two or three eggs in a nest in a tree, both sexes incubating.

The White-bellied Antbird is typically 15 cm long, and weighs 26 g. It has rufous brown upperparts and whitish underparts shading to cinnamon-buff on the flanks and lower belly. There is a long grey supercilium. The pink legs are long and strong, reflecting this bird's terrestrial lifestyle.

The male has a black face, throat and upper breast. The female has a darker crown, grey cheek patches and small dark spots on the wings, and lacks the black markings of the male. The northern race griseopectus has black spots on the wings and grey central underparts in both sexes.

The White-bellied Antbird is an insectivore which feeds on ants and other arthropods at or near the ground; it sometimes follows columns of army ants. It may be located by its bright descending jeer-jeer-jeer-jeer-jeer-jeer-jeer-jeer-jeer-jeer-jeer-jeer song, which ends with a few chew notes.