Benthic foraminiferal content of the sediment samples from the thermal region located at the Ilıca Bay and surroundings was taxonomically investigated. A total of 40 calcareous foraminiferal species from the 12 families and 23 genera have been described. Some thermal springs of the Ilıca Bay and surroundings with a temperature of 42°C -62°C, set up a various ecological environment. As a result of this event, some peneroplids which are not able to carry on their life under the Aegean Sea conditions wityh a temperature of 9°C -26°C and dissolved oxygen content of 4-10 ml/l appear. These peneroplid species of Coscinospira hemprichii Ehrenberg, Laevipeneroplis karren (Wiesner), Peneroplis pertusus (Forskal) and Peneroplis planatus (Fichtel and Moll) were abundantly found together with the Sorites orbiculus Ehrenberg and other benthic foraminifera in the area under the thermal influence.