The influence of changes in atomic volume on the three types of hyperfine interactions (the isomer shift, the quadrupole coupling and the magnetic dipole interaction) is reviewed. The volume dependence of a hyperfine interaction is usually obtained from high-pressure experiments, which are discussed in some detail. Particular emphasis is given to the interpretation of the volume coefficients of the Mössbauer isomer shift in metals and compounds. The volume coefficient of a hyperfine interaction can be used to interpret other phenomena which are accompanied by volume changes. A typical example is the temperature dependence of hyperfine interactions in solids. A selection of measurements of this kind is discussed to give some insight into the problems connected with such investigations