In this study, it is aimed to determine to petrographical, geochemistry and sources of the Yürekli volcanics (Biga Peninsula, NW Turkey). Tertiary volcanism is widespread in Western Anatolia (NW Turkey), is an important area where tectonic and magmatic events are observed together. Yürekli volcanic rocks composed of dacitic lavas and pyroclastics. Dacitic lavas show porphyric and hyaloporphyric texture, and consisting of plagioclase, quartz, amphibole, biotite, sanidine and Fe-Ti oxide minerals with apatite and zircon accessory minerals. Petrologically, it is high-potassic and calc-alkaline in characteristic. Yürekli volcanics show enrichment in large ion litophile elements (LILE) while depletion in high fi eld strength elements (HFSE) on the N-MORB normalized diagram. On the chondrite-normalized rare earth element (REE) plot, light rare earth elements are enriched but heavy rare earth elements are depleted in the rocks. Besides, REE patterns are concave shaped (mean LaN/LuN=16-25), and show a slight negative Eu anomalies (0.66-0.81). Plagioclase, amphibole and biotite fractional crystallization and crustal assimilation are important in the evolution of the Yürekli volcanics. According to all data, it can be argued that the Yürekli volcanics is formed in the post-collisional setting, and their parental magmas have derived from the melts of enriched lithospheric mantle.