A year-long evaluation is underway in a cardiac unit in Wales to see whether a switch to using Dyna-Form Static Air HZ for every patient (apart from when they are in Cardiac Intensive Care) would reduce the number of hospital-acquired pressure ulcers (HAPUs) on the unit and also reduce the amount of money that was previously being spent on alternating pressure mattresses. Patients in this group have a particularly high risk of pressure ulcer development, and in the previous year 19 cases were documented. This article reports on the interim findings 5 months into the evaluation and discusses the problems of conducting an evaluation in a busy clinical environment. As yet, there have been no reported HAPUs in the 383 patients placed on the mattress to date. The attempt to reduce the number of pressure ulcers in this environment is part of the zero tolerance to pressure ulcers inspired by the 1000 lives campaign.