About 3,000 km of geophysical profiles (sparker and air gun) were shot off southeastern Peloponnesus during several cruises in 1976-77 as part of a general study of the active Hellenic margin. These data, supplemented by the results of previous surveys, provide a basis for mapping the overall structure of the area. The main margin depocenters lie on the upper slope where they are represented by tectonically bounded plateaus and basins. The lower to middle slope is an area of little sedimentation but intensive tectonization, thus an area of numerous basement ridges and zones of deformed sediments. In contrast, the base of the margin is characterized by discontinuous, deep, and sediment-filled depressions--the North Matapan Trough and the South Matapan Trough, separated by region of prominent topography, the Matapan Seamounts. Two main trends (N 140° and N 70 to 80°) control the structure of the area; both can tentatively be interpreted in the light of compression originated by subduction acting along the Ionian margin.