Geothermal waters have various and wide usage areas, but the main ones are; They are used for electricity generation, heating and cooling, processing of fruits and vegetables, greenhouse activities, aquaculture, swimming, bathing and health tourism. This presentation is about the compositions of geothermal fluids in different compositions and their possible effect mechanisms on health. The possible effects and effect mechanisms of possible cations and anions in thermal waters of some locations in the Aegean region on human health will be discussed.