The aim of this study was to evaluate the pressure ulcer prevention efficacy of an alternating pressure air mattress in elderly patients. A randomised, single-blind study was performed with 120 elderly patients suffering from chronic bedsores or pressure ulcers to test the effect of sleeping on an alternating pressure air mattress (APAM) on pressure ulcer incidence. Patients were randomly assigned to two groups: one that slept on their regular bed and the other that slept on the APAM. The study demonstrated a significantly reduced incidence of pressure ulcers in the group sleeping on the APAM (18% vs 44%, p=0.022). Our findings suggest that using an APAM may be an effective method for preventing pressure ulcers in elderly patients suffering from chronic bedsores or pressure ulcers.