AbstractExperiments are reviewed in which the photoreactions of the visual pigments rhodopsin and octopus rhodopsin have been investigated by FTIR spectroscopy. It is shown that from the spectra important characteristic structural elements can be derived for the dark state as well as for the intermediates. Since the spectra contain contributions from the chromophore as well as from the protein, methods are described which allow one to discriminate between them. In the case of rhodopsin, the influence of single amino acids on spectra and function is assessed by investigations of specific mutants. The role of the chromophore‐protein interaction for the photoreaction and the activation mechanism is addressed by studies of modified rhodopsins containing retinal analogues as chromophores. Characteristics of the active state, which is capable of transducin activation, are especially emphasize