Between April and October 2012, 20 juvenile and adult green frogs (Lithobates clamitans) were collected by hand or dip net from 3 counties in Arkansas and examined for coccidial parasites. A single frog (5%) was found to be passing oocysts of a previously unknown eimerian species. Oocysts of Eimeria menaensis n. sp. were ellipsoidal with a bilayered wall and measured (length [L] × width [W]) 25.4 × 15.6 (23–27 × 13–17) µm, with a L/W ratio of 1.6. A micropyle was absent but an oocyst residuum and polar granule were present. Sporocysts were spheroidal to subspheroidal and measured 5.0 × 5.0 (4–6) µm with L/W of 1.1. An indistinct Stieda body was present, but sub- and para-Stieda bodies were absent. The sporocyst residuum consisted of condensed granules dispersed between sporozoites. Sporozoites were elongate and attenuated at both ends with spheroidal anterior and posterior refractile bodies. This represents the second report of coccidia from L. clamitans and the first time a coccidian has been reported from a green frog from Arkansas.