The Tavsanli Zone in northwest Turkey is intruded by many Late Cretaceous to Eocene (91-45 Ma) calc-alkaline granitoids, of which the Günyüzü pluton in the Eskisehir region is the least studied. The Günyüzü rocks are high-K, calc-alkaline (I-type) intrusions, and are comprised of diorite, granodiorite, granite, and granite porphyry. Typical minerals are plagioclase, K-feldspar, quartz, biotite, hornblende and Fe-Ti oxides. Chondrite-normalized REE patterns for the Günyüzü rocks are moderately fractionated and have small negative Eu anomalies. They are enriched in LILE and LREE relative to HFSE, showing characteristics of arc-related granitoids. Low values of molar K₂O/Na₂O, Al₂O₃/(FeO+MgO+TiO₂), and (Na₂O+K₂O)/(FeO+MgO+TiO₂) ratios demonstrate that the Günyüzü magma(s) were produced from mafic lower crustal rocks.