The effect of deformation on the excitation of multiple giant dipole resonances is studied. Analytical expressions are derived in the framework of the interacting bosom model for the energies and El properties of giant dipole resonances in spherical and deformed nuclei, and a numerical treatment of transitional nuclei is proposed. Coulomb-excitation cross sections are calculated in U-238 and in the samarium isotopes. (C) 1999 Published by Elsevier Science B.V. All rights reserved.