Palaeo- and neo-tectonic evolutions of the Gulf of Saros, northwestern Turkey, were investigated based on geological mapping, geomorphology, seismicity and GPS measurements. In this area three overlapping basins were differentiated: the Thrace, Enez and Saros basins. The Thrace basin opened during the middle Eocene on the continental Strandja Massif as a post-collisional, fault-controlled extensional basin after the closing of the Intra-Pontide Ocean to the south. This basin reached its greatest extent during the Late Eocene-Early Oligocene and then, turned into an intramontane terrestrial basin from the middle Miocene onwards. The Enez basin opened along the southern margin of the former Thrace basin as an E-W-trending half graben during the middle Miocene. The, age and geometry of this basin corresponds to the extensional basins of the Aegean graben system to the south. Stratigraphy and structures related to the North Anatolian fault indicate that the fault started to be active since Pliocene and modified older structures. The fault zone evolved in two stages in and around the Gulf of Saros. During the initial stage the fault was trending as a single segment with a transpressional nature and without any stepping, and caused thrusting and folding subparallel to the main trace of the fault. Since the Late Pliocene the fault was left-stepping in the Saros area, giving rise to the Saros pull-apart basin. We modelled these two stages by using boundary element method, and found that there is a good correlation between the modelling results and geology and geomorphology. (C) 1998 Elsevier Science B.V. All rights reserved.