This study was conducted in order to determine the seasonal changes in the forage quality of Kermes Oak under Mediterranean region of Turkey in 2013-2014 years. Leaf samples were taken as 150 number in the middle of each month from the same geographical sides and altitude. The leaf width, leaf length, crude protein (CP) ratio, neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrient (TDN) and relative feed value (RFV) were determined in this research. According to results, the highest leaf width and leaf length were determined on samples taken in July and August. The highest ADF and NDF values were obtained from samples taken in October and November The samples taken in February, March, April and May had the highest TDN and RFV values.