Patients with developmental disabilities may be at higher risk for patient safety events in hospitals. This study used data from the Learning from Lives and Deaths (LeDeR) program in the UK to examine the prevalence of five avoidable in-hospital safety events. Compared to the general populations, patients with developmental disabilities experienced more patient safety incidents, longer length of stay and increased risk of death. Although the data did not include the causes of the incidents, the results support improving both inpatient and community care for persons with developmental disabilities.