Geothermal systems of the area are divided into two sub systems belonging to the B.Menderes Graben's geothermal systems, the Gumuskoy and Sazlikoy geothermal systems. The thermal waters of the area have outlet temperatures of 40 degreesC, EC of 4960 to 5079 muS/cm, and of Na-Ca-Cl-HCO3 type in Gumuskoy system and 25 degreesC, EC of 1490 muS/cm, and of Ca-HCO3 type in Sazlikoy system, respectively. They issue from Menderes Massif rocks, which are made up of various types of schists and marbles. A comparison of new data with historical records indicates that the percentages of the major ion compositions and temperature of the thermal waters in the area do not show significant variation through time. Geochemical assessments suggest low enthalpy (average reservoir temperatures between 60-80 degreesC) geothermal systems. All the thermal waters in the area fall into the immature fields indicating that none of these waters have attained equilibrium with their associated host rocks.