Oocysts of Eimeria oryxae sp. n. are described from the faeces of the scimitar-horned oryx, Oryx dammah (Cretzschmar, 1826), from Zoo Garden, Riyadh City, Saudi Arabia. Sporulated oocysts were ellipsoid in shape measuring 20.9 x 17.1 (16.7-24.2 x 15.5-20.2) microm, with smooth brownish-yellow double layered wall. Micropyle and ellipsoidal polar granules are present, but micropylar cap and oocyst residuum are absent. Sporocysts are ovoid, reaching 10.0 x 5.7 (9.2-11.0 x 5.2-6.5) microm with Stieda body and sporocyst residuum. Sporozoites are elongated, each with large and small refractile body.