The knowledge of the electronic excited states dynamics in light harvesting pigment-protein complexes is most essential for the understanding of structure function relationship in these complexes at molecular level. Improved structural data as obtained in the last years for LH2 of purple bacteria and LHC II of higher plants, an increasing number of spectroscopic data, especially those with fs and ps time resolution, as well as improved quantum mechanical methods give the basis to discuss the energy transfer in photosynthetic antenna complexes more generally beyond the mostly used model of incoherent Forster transfer between localized chlorophyll states.

New experimental results for LHC II of higher plants are discussed as well from fs time resolved measurements as from measurements in the frequency domain especially with respect to the exciton-phonon interaction. It is shown that the energy transfer can adequately be described in terms of the model of extended exciton states weakly coupled to the heat bath and the relaxation between them.