A 2D modeling of geoid/quasigeoid data across the Pyrenees is consistent with electromagnetic images of the Pyrenean lithospheric structure, showing a subducted Iberian lower crust. Using new magnetotelluric data acquired through the orogen, a 3D electrical conductivity model of the Pyrenean lithospheric structure is obtained. The most outstanding feature is the presence of a high conductivity zone at lower crustal depths along the orogen in the contact zone between the Iberian and European plates. The integration of various geophysical parameters suggests that the simplest and most reasonable mechanism to explain the observed data is partial melting of the subducted Iberian lower crust. ¿ 2000 American Geophysical Union