Three isosporan species are described from the double-collared seedeater, Sporophila caerulescens from Eastern Brazil. Isospora sporophilae n. sp. oocysts spherical to subspherical; oocyst wall bi-layered, smooth, inner layer colorless to pale yellowish, 21.6 x 20.9 (19.20-23.20 x 18.40-22.60) microm, shape-index 1.03 +/- 0.02 (1-1.10), with no micropyle or oocyst residuum. Polar bodies splinter-like or comma-like. Sporocysts ovoidal, 15.2 x 10.6 (17.40-12.80 x 12.60-8.40) microm, shape-index 1.43 +/- 0.14 (1.17-1.81), with knob-like Stieda body and residuum. Large crystalloid body in the center of the sporocyst. Isospora flausinoi n. sp. oocysts spherical to subspherical, oocyst wall bi-layered, smooth, colorless, 17.30 x 16.53 (14-20 x 13.60-20) microm, shape-index 1.05 +/- 0.04 (1-1.21). Micropyle and oocyst residuum absent; presence of a large polar body. Sporocystpiriform, 14.88 x 10.70 (11.80-18 x 8-12.40) microm, shape-index 1.40 +/- 0.18 (1.07-1.77), with smooth, thin, single-layered wall. Sporocyst with rounded Stieda body with no substieda body, and residuum composed of granular material. Isospora teixeirafilhoi n. sp. oocysts spherical to subspherical, oocyst wall bi-layered, smooth, colorless, 17.41 x 16.81 (15.60 - 19.40 x 14.20-18.80) microm. Shape-index 1.04 +/- 0.08 (1-1.12). Micropyle and oocyst residuum absent; presence of a small double-lobuled polar body. Sporocyst ovoid, 11.74 x 8.12 (9-14.20 x 6.20-9.40) microm. Shape-index 1.46 +/- 0.23 (1.06-1.88). Sporocyst with knob-like Stieda body, no sub-Stieda body and residuum composed of granular material.