Radon gas is noble gas formed from the normal radioactive decay series of 238U. Uranium is present in almost all rocks but enriched in silica-rich rocks like granites, gneisses, schists, volcanics, pegmatites, migmatites. The study area extends over metamorphic, volcanic, and clastic sedimentary rocks. Soil radon was measured in 34 measuring points and its concentrations reach 3700 Bq/m(3). The mean values decrease due to seawater penetrations or to collections of atmospheric waters in a basin. Those water saturates the soil and prevents radon emanation and exhalation. The emanation of radon to the surface requires transporting agents. In geothermal fields, hot water or fluids take on this task. For that reason, geothermal fields can represent high soil radon. As radon was classified as a human carcinogen, our study area and whole Aydin province which has rich geothermal potential must be surveyed for public health.