Almazan Basin, localised in the northeastern part of the Iberian Plate, shows a characteristic drainage network formed by the Duero river, E-W trend in the main part of it trajectory, shifting suddenly into a N-S trend by the Almazan town. The morphological study based on a map subenvelopes and some asymmetry index suggest a relation with the N20a-30aE Spanish Central System tectonic trend. Moreover, the study of the morphologic surfaces, longitudinal profiles and the main faults, reveal a major river incision in the south slope, while the north slope tributaries fit into a more tectonically stable area. These two remarkable areas would be divided by a major uneveness, E-W trend, located underneath the Duero river. Present fluvial network is controlled by NW-SE and E-W to WNW-ESE fault systems.