Abstract: This study comprises the properties of Samandağ Formation (Piacenzian) exposed in a wide area between Antakya and Saman­ dağ (Halay), based on its molluscan faunal content. In thisframe 46 genus and 57 species have been determined in the samples, col­ lected fromfive measured stratigraphic sections. It has been revealed that the age of the formation is Piacenzian (Upper Pliocene)according to the faunal associations wich includes marineforms in the lower, and fluvialforms İn the upper levels ofthe successi­ on. This stand points to a change İn the environmental conditionsfrom normal marine to oligohaline, and faunal properties alsosuggest that the subtropical climatic conditions predominated in the region during the Piacenzian time.