ABSTRACT: Sanctus sinaicus nov. gen et sp. is described frommaterial collected in the uppermost part of the Khaboba Formation and througout the Tanka and Tayiba formations of Wadi Thal and Wadi Matulla in West–Central Sinai.We assign this new genus and species to the Late Eocene according to associated planktonic foraminiferal assemblages. Its test is symmetrical in axial sectionwith the division of chambers in the same section similar to that of amphisteginids in their early ontogenetic stage and lacks a canal system. In comparing Sanctus sinaicus with related amphistegenid species, such as Penoperculoides cubaensis Cole and Gravell 1952 from the Caribbean; Penoperculoides rozlozsniki (Méhes) ( ex: Nummulites rozlozsniki Méhes) fromHungary; and “Non Nummulites rozlozsniki†described by Sander 1962, from theDammamFormation of Saudi Arabia,we find that Sanctus sinaicus is similar to P. cubaensis in the type of coiling and the character of the umbo, which lacks alar prolongations, a canal system and transverse trabeculae, and differs from species of Nummulites in the central subdivision of chambers.