The length of Aegean arc in south-west Turkey has been deter mined by the use of intermediate focal depth earthquakes which occurred between 1900-1985 in the south-west of Turkey (34.00- 38.00 Nand 27.00-32.00 E). Intermediate focal depth earthqua kes in south-west Turkey revealed the presence of a seismic Benioff zone caused by underthrusting of the African litho spheric plate by the Aegean arc. In order to determine the geometry of underthrustin%detailed epicenter maps of the in termediate depth earthquakes in south-west of Turkey were pre pared. It is known that these earthquakes brought great harm in the past. Investigation of time distribution of them will help to predict the occurrence of them in the future. These intermediate focal depth earthquakes can be differenti ated from deep ones by their micro- and macroseismic proper ties. Papazachos (1969) and Comninakis (1970) found that the foci of these earthquakes are in a zone underthrusting exten ding from the East Mediterranean to the Aegean arc. Morgan (1968) and Le pichori (1968) defined three plates which are important in East Mediterranean tectonics. These are the Afri ca, Arabic and Eurasian plates. They define wide earthquake belt on the boundaries between the African and Eurasian plate."