The uppermost Cretaceous Tarbur Formation of the Zagros region (SW Iran) is mainly siliciclastic in composition, though it also incorporates some carbonate units including several rudist lithosomes. Two sections through this formation, in the Semirom and Gerdbisheh areas, have been chosen for study of the lithosomes and their rudist fauna. These lithosomes vary in faunal content, geometry and internal organization (density and diversity). Preliminary investigation of the specimens collected from the studied sections reveals a diverse rudist fauna. Eleven genera and 23 species have been determined, belonging to the rudist families Hippuritidae, Radiolitidae and Dictyoptychidae. These rudist assemblages indicate a Maastrichtian age for the Tarbur Formation in these areas. With regard to their growth geometries, most of the specimens are of elevator rudist morphotype, forming many different associations (e.g., bouquets and clusters). Comparison between the present rudist fauna, particularly taxa considered endemic to this part of the Mediterranean province, with the Late Cretaceous fauna recorded from other parts of the Zagros, Turkey and South of the Persian Gulf (Oman and UAE) show similarities that confirm the faunal connection between them.