Discusses the tectonic relationships of Pennine structural elements and the sources of Prealpine nappes in the Savoy (France)-Valais (Switzerland) region. The source of the central Prealpine nappe seems to have been in the Subbrianconnais-outer Brianconnais zone. Plastic elements were thrust along Carnic (Triassic) gypsum beds, whereas rigid elements were dislocated along Werfenian (Triassic) gypsum. Between the Ultradauphinois- Ultrahelvetic and the Subbrianconnais zones, north of the Arc river, lies the Valais zone which had an independent paleogeographic history. The source of the upper Prealpine nappes is still uncertain.