Abstract: Twenty brachiopod species and thirty five genera belonging mainly to superfamilles of Lingulacea,Orthacea, Enteletacea, Plectambonitacea, Strophomenacea, Atrypacea are identified from two different localities onthe eastern side of the Bosphorus. These fossils show different faunal associations.One locality is near Çengelköy and yields conulariids and brachiopods in chamozitic beds («Çengelköy Chamosite»), the type locality within so-called «Laminated Shales». These fossil associations belong to the Exoconulariaistanbulensis-Aegiromena Zone and are of Middle Ordovician (Late Llandeilo-Early Caradoc) age.The second locality is 1,5 km north of Pendik, east of Istanbul. The studied horizons correspond to younger bedsin the «Laminated Shales» and are termed «Bryozoan Shales» These were formerly thought to be Upper Silurianor Early Devonian (Gedinnian) age. In this study, the new collections show that the «Bryozoan Shales» whichcontain mostly Orthida, are of Upper Ordovician (Late Caradoc-Ashgill) age. They include Orthambonites calligramma, Orthambonites humilidorsatus, Nicolella actoniae, Hesperorthis cf- eraigensis, Glytorthis aff. maritima, Saukrodictya hibernica, Drabovia sp., Leptestiina prantli, Anizop leurella tricostellata, Strophomena aff. planumbona, Christiania sp-, Catazyga sp. and together with the ostracod genera Uhakiella sp., Pseudoulrichia sp-, and the bryozoansDicranopora sp. and Atactotoechus sp.These Upper Ordovician (Upper Caradoc-Ashgill) brachiopod assemblages show close affinity to those of Bohemia, Great Britain, France, Spain, Sweden, North Africa, Ireland and North America- Therefore the content of shellyfauna indicates the cosmopolitan nature of the Mediterranean and the North European Provinces.