Abstract: The reefoid limestones which crop out along the Southern foothills of Istranca Mountains have become attractive in the last decade,especially for petroleum exploration companies. There exist some workswhich are particularly focussed on those limestones contemplated as apromising reservoir rock for oil exploration in the Ergene Basin.The most characteristic portions of the reefoid limestones are located inthe Pınarhisar ,and vicinity. İn that sector the gentle southerly dippinghomocline of Tertiary deposits, overlies the metamorphic basementof Paleozoic / older (basement comlex) rocks. The studied sedimentary sequence consist of classics ,and marl (İslambeyli formation), thecomformably overlying oolite bearing pellet limestone of Oligocene age (Pınarhisar formation). The investigation is limited by the basement complex ,and Miocene (?)beds which comformably overly the Pınarhisar formation to the north ,and south respectively.The limestones of the Pınarhisar reef complex which cover 2/3 of thestudied ares, were diveded in reef elements by both field ,and microscopic observations.Folk’s limestone classification was generally used for naming the carbonate samples, excluding the terms used in field studies.