A species of Eimeria new to science was discovered in fecal samples of mourning doves (Zenaida macroura) from Kentucky, U.S.A. Oocysts (n  =  57) are spherical to ovoid, 24.2 μm ± 0.6 × 20.7 μm ± 0.4 (23–25.5 μm × 20–21.5 μm), with an average length/width (L/W) ratio of 1.2 (1.1–1.3). The oocyst wall is double layered, smooth, and colorless. The outer wall is 1 μm, and the inner wall is extremely thin. Oocyst residuum and micropyle are absent, but 0–2 variably shaped polar granules (PG) are present. Most PG are sausage shaped (1 × 1.5 μm), while others are round or globular (~0.8–1 μm). Among the 57 oocysts, 54 had 1 PG, 2 had two PG, and 1 oocyst lacked a detectable PG. Sporocysts (n  =  83) are ovoid, 12.4 μm ± 0.5 × 7.3 μm ± 0.3 (12–13.8 μm × 6.9–8 μm), with an average L/W ratio of 1.7 (1.5–1.9). A knob-like Stieda body continuous with the sporocyst wall and a rounded substieda body are present. The sporocysts contained a sporocyst residuum made up of numerous granules of a uniform size (1 μm). Sporozoites are smooth with a terminal refractile body present. This is the third description of an Eimeria species from the genus Zenaida (Columbiformes: Columbidae) and the first report of Eimeria from the mourning dove.