The Upper Devonian Maple Mill Shale Formation in southeastern Iowa, U.S.A., has yielded a diverse and unusual ostracode fauna consisting of eighteen benthic species and one (probably planktonic) entomozoacean species. Only two species have been previously described. Although the remaining species are considered new, because of poor preservation only three are named herein: Triceratina lethiersi n. sp., Graphiadactylloides kalonaensis n. sp. and Entomozoe (Nehdentomis?) kindlei n. sp. At the species level the fauna is unique. The absence of Bairdiacea suggests a low oxygen (hypoxic) environment. Conodonts indicate that the ostracode-bearing layer correlates with the Scaphignathus velifer Zone and fragments of cephalopods indicate the Platyclymenia do III-IV Zone.