This paper presents a correlation of thermal structure with seismic activity of southeastern Aegean Sea and western part of Turkey. The reduce to pole method was applied to magnetic data and the magnetic map obtained from reduce to pole correction was divided into 132 overlapping blocks with the sizes 90 x 90 km for estimating Curie Point Depth. These depths were varied from 9.8-19.5 km whereas heat flow values were found to be 50-125 mW m(-2). Generally, the region is characterized by shallow Curie Point Depth values because of the continental extensional regime in N-S directions and subduction zone. Furthermore, radiogenic heat production values were calculated as 0.21 - 0.51 mu Wm(-3) and the distribution of these values showed that high radiogenic heat values associated with the region where high heat flow values were seen. Seismotectonic activity in the region implies that the deep-focus earthquakes (180 km) occurred in the subduction zone and these earthquakes were characterized with high heat flow zone in the Aegean Sea. All the results have shown good agreement with geological and tectonic regime of the Aegean Region.