To estimate the prevalence of pain in adult patients attending an emergency department (ED) and to identify risk markers for insufficient pain relief, a cross-sectional survey was conducted for 16 days, 24 hours each day, in the ED of a Paris university hospital. A structured questionnaire was used to collect characteristics of pain and its management from patients. Pain intensity was evaluated both on arrival and before discharge using two scales (a numerical descriptor scale or a verbal pain intensity scale). On arrival, 78% of the patients complained of pain; among them, 54% complained of intense pain and 47% suffered procedural pain. Insufficient pain relief was assessed in 289 (77%) patients. We identified the following risk markers for insufficient pain relief: moderate or low pain intensity, no intervention in the ED before the medical examination, and no use of medication before arrival.