Pressure sores are a potential complication of intensive care. Modern methods of pressure sore prevention centre around the use of pressure-relieving devices. Few studies exist that confirm the effectiveness of these devices. This study evaluates the effectiveness of two devices, the Hill-Rom Duo mattress and the KCI TheraPulse. High-risk patients were randomly assigned to receive one of two devices. We excluded those patients who had pressure sores upon admission. Those patients that did develop a pressure sore had their wound digitally photographed and graded by two independent tissue viability nurses. Sixty-two patients were included (30 TheraPulse, 32 Duo. Nine developed a pressure sore (6 Duo, 3 TheraPulse). No statistical differences between the two devices could be found. The longer a patient was nursed on a device, the greater the risk of pressure sore development. Despite the use of these devices, pressure sores can still develop in the Intensive Care patient population.