Unlabelled: Pressure ulcers represent a major current health problem and produce an important economic impact on the healthcare system. Most of studies to prevent pressure ulcers have been carried out in hospital contexts, with respect to the use of hyperoxygenated fatty acids and to date, no studies have specifically examined the use of olive oil-based substances., Methods and Design: Main objective: To assess the effectiveness of the use of olive oil, comparing it with hyperoxygenated fatty acids, for immobilised home-care patients at risk of suffering pressure ulcers. Design: Non-inferiority, triple-blind, parallel, multicentre, randomised clinical trial. Scope: Population attending Primary Healthcare Centres in Andalusia (Spain). Sample: 831 immobilised patients at risk of suffering pressure ulcers., Results: The follow-up period was 16 weeks. Groups were similar after randomization. In the per protocol analysis, none of the body areas evaluated presented risk differences for pressure ulcers incidence that exceeded the 10% delta value established. Sacrum: Olive Oil 8 (2.55%) vs HOFA 8 (3.08%), ARR 0.53 (-2.2 to 3.26) Right heel: Olive Oil 4 (1.27%) vs HOFA 5 (1.92)%, ARR0.65 (-1.43 to 2.73). Left heel: Olive Oil 3 (0.96%) vs HOFA 3 (1.15%), ARR0.2 (-1.49 to 1.88). Right trochanter: Olive Oil 0 (0%) vs HOFA 4 (1.54%), ARR1.54 (0.04 to 3.03). Left trochanter: Olive Oil 1 (0.32%) vs HOFA 1 (0.38%), ARR0.07 (-0.91 to 1.04). In the intention to treat analysis the lower limit of the established confidence interval was never exceeded., Discussion: The results obtained confirmed that the use of topical extra-virgin olive oil to prevent PU in the home environment, for immobilised patients at high risk, is not inferior to the use of HOFA. Further studies are needed to investigate the mechanism by which olive oil achieves this outcome., Trial Registration: Clinicaltrials.gov NCT01595347.