Because critical care nurses recognize that many of their patients are at risk for pressure ulcer development, they provide them with support surfaces that can reduce this risk. Few reported studies, however, are available to help these nurses choose these surfaces wisely. This project was a new-product evaluation that compared the clinical effectiveness of three types of support surfaces: two dynamic mattress replacement surfaces and a static foam mattress replacement. Members of a convenience sample of 110 patients admitted to a surgical Intensive care unit each used one of the three support surfaces. When each patient was placed on one of the three surfaces, the eyaluators rated likelihood of pressure ulcer development (Braden Scale score) and assessed the skin for pressure ulcers. The evaluators repeated the Braden Scale score weekly and the skin assessment three times each week. Nine patients (8%), three patients on each support surface, acquired pressure ulcers. The logrank test did not find a statistically significant difference between the three types of support surfaces with respect to the risk of pressure ulcer development. Stepwlse Cox proportional hazards regression revealed a statistically significant relationship between the risk of developing, a pressure ulcer, the averaged total Braden Scale score, and the averaged score for the sensory perception subscale of the Braden Scale. Although these three surfaces were comparable In effectiveness, they were not comparable In cost. Both dynamic mattress replacement surfaces cost approximately $2000 each, whereas the cost of the static foam mattress replacement was only $240 each. The results of this product evaluation should encourage other nurses to evaluate patient care products carefully before making recommendations.