Three new coccidian (Apicomplexa: Eimeriidae) species from the buffy-fronted seedeater Sporophila frontalis Verraux in Brazil are reported in the current study. Isospora frontalis n. sp. oöcysts are spherical to sub-spherical, 27.9 x 26.9 mum, with a smooth, bi-layered wall c.1.4 microm thick. A micropyle and an oöcyst residuum are absent, but polar granules are present. Sporocysts are elongate ellipsoidal, 19.6 x 11.1 microm. The Stieda body is knob-like and the substieda body is slight. The sporocyst residuum is composed of scattered granules, and the sporozoites are vermiform with a refractile body and a nucleus. Isospora teresopoliensis n. sp. oöcysts are spherical to sub-spherical, 25.7 x 24.3 microm, with a smooth, bi-layered wall 1.3 microm thick. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ovoid, 18.8 x 11.2 microm. The Stieda body is nipple-shaped and the substieda body is large and prominent. The sporocyst residuum is composed of scattered granules, and the sporozoites are large and elongate, with a refractile body and nucleus. Oöcysts of Isospora chanchaoi n. sp. are spherical to sub-spherical or ovoid, 24.2 x 22.0 microm, with a smooth, bi-layered wall c.1.2 microm thick. Both a micropyle and an oöcyst residuum are absent, but one or two polar granules are present. The sporocysts are ellipsoidal, 16.1 x 10.3 microm. The Stieda body is nipple-shaped and the substieda body is small but prominent. The sporocyst residuum forms a compact mass of granules, and the sporozoites are large and elongate, with a refractile body and a nucleus.