Abstract: The Karakaya Complex consists of four different tectonostratigraphic units of similar age and reflects different tectonic and basin conditions. These units are Nilüfer, Hodul, Orhanlar Greywacke and Çal. unit. The Nilüfer unit consists mostly of metabasite and metasandstone with a small amount of quartz calcschists and marble overlying them. The Hodul unit, the most common unit in the Karakaya Complex, consists of light grey-white feldspar sandstone and dark grey-black shale siltstones. It is possibly a member of the Kaşal Limestone deposited ina narrow, intermittent area on a muddy sea floor in the form of lens-like ground reef dunes / benches. The Orhanlar Greywacke is composed of limestone and lesser spilite blocks, monotonous grey wacke and shale matrix within the Karakaya Complex. The Çal unit consists of pelagic limestone and burgundy-brown coloured radiolarites, mudstone levels and wide spread limestone olistoliths. In this study, the biostratigraphy of a Kaşal Limestone Member of the Hodul Unit of Karakaya Complex has been examined in SW İvrindi (Balıkesir). The geology of Kaşağıl Village, which is located 15 km SW of İvrindi, is characterized by a clastic matrix and Permian-Upper Triassic limestone blocks. Permo-Triassic foraminifers were obtained from the samples collected from the studied area and macrofossils were obtained such as ammonite, brachiopod fragments, crinoid, echinoid and gastropod fragments. Involutina ? jurassica JONES form was obtained from the strata forming the youngest levels in the measured stratigraphic sections.