Structural analysis of late Cretaceous sequences from the northeastern Tunisian Atlas, led to conclude on an active basin floor instability. Regional tectonics resulted in tilted blocks with a subsidence reorganization, since the Campanian time. These structural movements are controlled both by N140 and N100-120 trending faults. The Turonian-Coniacian and Santonian sequences display lateral thickness and facies variation, due to tectonic activity at that time. During Campanian-Maastrichtian, a reorganization of the main subsidence areas occurred, the early Senonian basins, have been sealed and closed and new half graben basins developed on area which constituted previously palaeohigh structures. These syndepositional deformations are characterized by frequent slumps, synsedimentary tilting materials, sealed normal faults and progressive low angle unconformities. These tilted blocks combined to a subsidence axis migration were induced by a NE-SW trending extensional regime. This extension which affects the Tunisian margin during the Upper Cretaceous, is related to the Tethyan and Mesogean rifting phase which resulted from the combined movements of the African and European plates.