Temporal aspects related to the Mössbauer resonance are reviewed, in particular time-dependent transient effects produced by high-frequency modulation of the recoilless gamma radiation. These phenomena are in many respects similar to those observed in NMR and laser spectroscopy. Transient effects can be described within a classical field model in terms of phase modulation of recoilless gamma radiation. Experimentally, use of the very narrow Mössbauer resonance of67Zn gives access to undisturbed transient phenomena without excessive difficulties due to nonideal modulation. Application of transient experiments facilitates determination of several physical parameters, of which some arc tedious to evaluate by other methods.