Fault plane solutions for 127 earthquakes, of magnitude M >= 5.5 and shallow focal depth (h< 60 km), which occurred in the Aegean Sea and surrounding area (34°N-43°N, 18°E-30°E) during the period 1953-1995, are used to investigate the active tectonics. The geographic distribution of the foci of these earthquakes and the similarity of the fault plane solutions led to the identification of 35 spatial clusters, which in turn define five seismic belts of similar seismotectonic properties. The first belt covers the coastal area of western Albania and western Greece, and is characterized by low angle thrust faults that strike parallel to the coastline (strike: ξ = 328°, dip: δ = 32°, rake: λ = 90°). This narrow zone of thrusting is attributed to the continent-continent collision between the Eurasian and Adriatic plates. The second belt is also of thrust type and extends along the convex side of the Hellenic arc (west of Zante to west of Rhodos). Faults of this belt have an approximately NW strike (ξ = 310°, δ = 24°, λ = 102°) and are attributed to subduction of the eastern Mediterranean oceanic lithosphere (front part of the African plate), and postienlarly to overthrusting of the Aegean plate onto the eastern Mediterranean lithosphere. The third belt is a very wide tensional one and covers most of the Aegean Sea and parts of the adjacent lands (eastern mainland and northern Greece, western Turkey, southern Bulgaria, southern former Yugoslavia). Normal faults in this belt strike in an approximately E-W direction and their dip angles are of the order of 45°. This kind of faulting is attributed to internal deformation, probably caused by gravitational collapse of the expanding area. The fourth belt is also tensional, but faults here strike in an approximately N-S direction. This belt starts in the north from Albania, follows the Hellenides Mountain Range down to eastern Epirus, then is probably interrupted, and is identified again in the southern Peloponnese through the Cretan trough to Rhodos. The cause of deformation in this belt is still a matter of controversy and there is no satisfactory interpretation yet. The fifth belt involves dextral strike-slip motion and marks the boundary of the Aegean plate with the Eurasian plate. This belt starts at the North Anatolian fault in the east, crosses the northern Aegean Sea, stops abruptly against central Greece before becoming evident again along the Cephalonia - Lefkada transform fault zone in the west. Faults in this belt are dextral strike-slip (ξ = 47°, δ = 80°, λ = 176°) and they take up the fast south westward motion of the Aegean plate relative to the Eurasian and African plates.