The effects of pressure on the remanent magnetization of rocks may well be important in regions of low geothermal gradients, for example subduction zones, or at localities where a magnetization is associated with a meteorite impact. In a series of experiments undertaken to determine the effects of hydrostatic pressure on the saturation magnetic remanent moment in a variety of materials, a 'pressure demagnetization' has been observed. From these experiments we conclude that there is a relationship between coercivity and the extent of this pressure demagnetization for rocks bearing magnetite and titanomagnetities.