DOUBLE PHOTO-EXCITATION OF ELECTRONIC STATES IN SOLIDS AND SURFACES J.Berakdar Max-Planck-Institut f\"ur Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany This work deals with the theoretical treatment of the two-electron excitation in solids and surfaces. It is shown that this excitation process is strongly dependent on the electronic correlation. Numerical results are presented and compared with recent experimental data.