Older patients represent an increasing population in emergency department (ED) with underlying diseases and longer ED length of stay, which are potential risk factors of pressure ulcers (PUs). The aim of the study was to determine the prevalence and incidence rates of PUs in an Emergency Department and to analyse variables related to PUs occurrence. The study was carried out in the Emergency Department of Bordeaux (France), and included 602 patients from 1 to 15 June 2010. All the potential body sites of pressure were examined at admission and discharge for all the patients by trained nurses. Comorbidity score, list of treatment, length of stay (hours), PUs (including stage I) and C-reactive protein (CRP) level were systematically recorded. A total of 47 (7·8%) patients had prevalent PUs at admission and 74 (12·3%) at discharge. The cumulative incidence was 4·9% and the incidence density was 5·4 per 1000 patients per hour. In multivariate analysis, higher comorbidities (OR 1·3; P = 0·014) and CRP levels (OR 1·005; P = 0·017) were both independent risk factors for developing PU. In conclusion, these data show that even a very short stay to the ED is sufficient to induce PUs especially stage I.