Chemical and structural data give new insight into the complex metamorphic evolution of crystalline basement of the Helvetic Realm (Central and Western Alps). The relics of pre-Carboniferous basement — the so called External Massifs — may be subdivided into an older basement unit with a younger cover, which together suffered the following metamorphic evolution from late Caledonian until Variscan times: These results confirm that the External Massifs have to be interpreted as pieces of a former continental crust with a metamorphic evolution known from the mid-European Variscan crystalline basement.