The book presents the results of the examination of geothermal waters in the Southern Serbia ( Sijarinska spa, Vranjska spa and Bujanovacka spa ) in the last twenty years. Geothermal waters' physicochemical properties have been examined, as well as their tendency to form deposits. On the basis of the performed examinations, it can be concluded that these geothermal waters show enormous potential which has been insufficiently exploited so far. As an illustration,a dryer pilot plant in Sijarinska spa has been shown.