Thirty-two chronic neurologic patients between 19 and 60 years of age were randomly assigned, for a period of three months, to either an alternating air mattress or a silicore mattress to test the preventive qualities of special mattresses in the occurrence of decubitus ulcers. The two groups were comparable on the variables of age, weight, diagnoses, history of disease process, history of being wheelchair bound, history of previous pressures, and mean scores on Norton's scale of risk, which is based on the subject's physical condition, mental alertness, ambulation, mobility and incontinence. No significant differences were observed in the preventive qualities of the two types of special mattresses in terms of the incidence, location, severity, or healing duration of the subjects' decubitus ulcers. Improved studies of common special mattresses are suggested.