To determine, in critically ill patients at risk, both the clinical utility and cost-effectiveness of using an air suspension bed in the prevention of pressure ulcers. Randomized, parallel group, controlled clinical trial with accompanying cost-effectiveness analysis. 30-bed multidisciplinary intensive care unit. 100 consecutive patients at risk for the development of pressure ulcers randomly assigned to receive treatment on either an air suspension bed or a standard intensive care unit bed. Patients considered at risk were those at least 17 years of age with an Acute Physiology and Chronic Health Evaluation II (APACHE II) score greater than 15 who had an expected intensive care unit stay of at least 3 days. The development of pressure ulcers by site and severity and the costs associated with each of the two programs. The air suspension bed was associated with fewer patients developing single, multiple, or severe pressure ulcers. In patients at risk, the use of an air suspension bed in the prevention of pressure ulcers was a cost-effective therapy. Despite intense nursing care, pressure ulcers are more prevalent in the critically ill patient population than in the general hospital population. Air suspension therapy provides a clinically effective means of preventing pressure ulcers in these patients. In patients at risk, air suspension therapy was a cost-effective means of managing pressure ulcers compared with the standard hospital bed.