From Early Miocene to the present-day the core parts of the western European Alps experienced brittle extensional deformations, mostly in a strike-parallel direction. Here we present new data constraining the brittle deformation of the Vanoise area (French Alps) and a synthesis of 312 paleostress tensors in the whole arc of the internal Western Alps. The data show a continuous change in the direction of extension, from N065° (Simplon area), to N-S (Vanoise area) and to NNW-SSE (Briançon area). The aboundance of orogen-perpendicular σ3 axes increases from the North to the South. In the Briançonnais area, an extensional reactivation of the Basal Penninic Thrust seems to be the origin of the E-W to NE-SW oriented σ3. In light of these new data and the regional paleostress synthesis, we propose a predominant orogen-parallel extension in the internal zone as a whole. This orogenparallel extension is related to the indentation/rotation of the Apulian microplate and to the opening of the Ligurian Sea during the Lower-Middle Miocene. The locally observed orogen-perpendicular extension is interpreted as an effect of the exhumation of the Internal Crystalline Massifs, the uplift of the External Crystalline Massifs and/or the present-day geodynamics (post-orogenic gravitational collapse). Some transcurrent tectonics, older than the extension in the Valais area, and younger than the extension further South is observed in the entire inner Western Alps; strike-slip movements are correlated with the Apulian rotation and local permutation of stress axes.