Absorption Spectra of a supramolecular complex (SC) placed in the proximity of a spherical metal nanoparticle (MNP) are computed. A description of the absorption is used that is based on a density,matrix propagation. The applied density matrix theory starts from a microscopic model including the Coulomb interaction between the SC and the MNP. This interaction is dominated by an energy exchange coupling between the excitations of the SC and the multipolar excitations of the MNP. Its nonperturbative consideration results in a shift and a broadening of all Frenkel-exciton levels as Well as an oscillator strength change. If a J-aggregate type SC near a MNP is considered, all exciton levels strongly contribute to the absorption what is in contrast to the isolated SC.