Study design: Prospective observational cohort study. Objectives: To describe time to occur and time until closure of hospital-acquired pressure ulcers (HAPUs) in patients with spinal cord injury (SCI). Setting: Specialised SCI acute care and rehabilitation clinic in Switzerland. Methods: Daily registration of the presence and severity of HAPUs in a consecutive sample of SCI patients during their entire in-patient stay. Results: Out of 185 observed SCI patients, 55 patients (29.7%) developed at least one HAPU. Within the first 30 days after admission, 50% of all HAPUs occurred. Less severe HAPUs occurred earlier than severe HAPUs. The occurrence of HAPUs was significantly associated with reason of admission (Po0.01), and was highest in first rehabilitation (51.4%) and orthopaedic surgery patients (41.4%). The incidences of first HAPU in these groups were 1.04 and 2.31 per patient-year, respectively. Patients in first rehabilitation or readmitted because of pressure ulcer (PU) showed an initial lower risk for HAPUs in the Kaplan-Meier curve compared with patients readmitted for other reasons. Cox regression analysis revealed an association between longer time since SCI and time until occurrence (P = 0.01). Closure of the HAPUs during hospitalisation was observed in 37 patients (67.3%) after 38.9 days on average. No significant associations were found between patient characteristics and time until closure. Conclusion: The dynamics of HAPUs varied according to admission reason and time since lesion. However, ongoing awareness to prevent HAPUs is needed in all patients with SCI.