Terminally ill patients may require sedation to relieve refractory suffering. The prevalence and modalities of this practice in palliative care services remain unclear. This study estimated the prevalence of all sedation leading to a deep unconsciousness, whether transitory, with an undetermined duration, or maintained until death, for terminally ill patients referred to a home-based or hospital-based palliative care service. We conducted a national, multicentre, observational, prospective, cross-sectional study. In total, 331 centres participated, including academic/non-academic and public/private institutions. The participating institutions provided hospital-based or home-based palliative care for 5714 terminally ill patients during the study. In total, 156 patients received sedation (prevalence of 2.7%; 95% CI, 2.3 to 3.2); these patients were equally distributed between 'transitory', 'undetermined duration' and 'maintained until death' sedation types. The prevalence was 0.7% at home and 8.0% in palliative care units. The median age of the patients was 70 years (Q1-Q3: 61-83 years); 51% were women and 78.8% had cancers. Almost all sedation events occurred at a hospital (90.4%), mostly in specialised beds (74.4%). In total, 39.1% of patients were unable to provide consent; only two had written advance directives. A collegial procedure was implemented in 80.4% of sedations intended to be maintained until death. Midazolam was widely used (85.9%), regardless of the sedation type. This nationwide study provides insight into sedation practices in palliative care institutions. We found a low prevalence for all practices, with the highest prevalence among most reinforced palliative care providers, and an equal frequency of all practices.< Réduire