An adapted version of the mattress system classification scheme described by Clark (1987; 1988) has been developed and its use illustrated with the classification of four mattress systems currently used in acute geriatric wards. The classification of these mattress systems was based upon measurements of trochanteric contact pressures. The verdicts of the classification scheme were compared with the established clinical use of each mattress, with broad agreement achieved. For example, a foam mattress used to protect patients at low risk of developing pressure sores was classified as suitable for use with "low" risk patients. However, several shortcomings to the classification of mattress systems solely upon trochanteric contact pressures were described in conjunction with requirements of a more comprehensive mattress system assessment.