Abstract: In this study, Ostracoda fauna of three deepest drilling samples (Çanankkale Formation), which have been derivedrom line drills, certified foot place of Çanakkale Bridge in Kilitbahir region has been determined. in these circum--tances, 111 samples from claystone, sandstone and marl sediments have been paleontologically evaluated.As result of systematic investigations and determinations, 27 taxa belonging to 8 families, 10 genera have been`etermined. Two species are described new as Cyprideis dardanellesensis n. sp., Heterocypris kilitbahirensis n. sp.and`e others 25 species have been known. These determined ostracoda assemblages clear/y indicate the middle-late Panonian ages. This age determination have been correlated and supported by using the other fossil group (spor-polens,astropods and chara). Ostrocoda fauna obtained in this study clearly reveals the transitional (shallow marine, lagoon, fresh water) environment. Due to dominance of ostracoda species and lithological properties of studied samples, it can be concludedthat mainly brackish (lagoonal) occasionally fresh water and saline water (sea) affects were prevailed in the environment. In the chronostratigraphic nomenclature, stage names have been chosen from Paratethyan ones, as most ofostracoda species belongs to Paratethys bioprovince.