Fossil freshwater molluscan shells and steinkerns have been found at Simanya, on the Southwestern Bank of the Cubango River in Northern Namibia. The occurrence of fossils resembles those reported from other sites in the "Grès Polymorphes" subunit of the Kalahari System of Central Africa. The aim of this paper is to describe and interpret the Simanya fossils and to discuss their stratigraphic and palaeoenvironmental contexts. The silicified deposits (chert, chalcedony) in which the snails occur were extensively used by prehistoric peoples for manufacturing of stone tools. Keywords: Chert, Chalcedony, Grès Polymorphes, Plio-Pleistocene, Gastropods, Fossils, Namibia.