Food products can be high-pressure processed (HPP) either in bulk or prepackaged in flexible or semi-rigid packaging materials. In the latter case the packaging material is subjected, together with the food, to high-pressure treatment. A number of studies have been performed to quantify the effects of high-pressure processing on the physical and barrier properties of the packaging material, since the integrity of the package during and after processing is of paramount importance to the safety and quality of the food product. This article reviews the results of published research concerning the effect of HPP on packaging materials. Copyright (C) 2004 John Wiley Sons, Ltd.