Background: Pain management in emergency departments is a complex objective. The absence of a care pathway or a high level of activity complicates diagnostic or analgesic therapeutic strategies. Medical innovation can impact both individual practices and the functioning of an emergency department.Objective: We then wanted to understand how medico-economic studies on pain were carried out in an emergency department.Study design: We reviewed the literature of the last 20 years (between 1998 and 2018).Setting: Of 846 titles screened, a total of 268 abstracts qualified for further screening, and 578 titles were excluded. A total of 14 studies qualified for inclusion in the review. Studies on medico-economics in an emergency department are very diverse. None of the methods used are identical; the studies differ in their very nature (prospective, retrospective, cost-effectiveness, etc.) and the determination of emergency room costs differs according to the part of the world studied. In addition, organizational impact is rarely measured, although it is an essential dimension for choosing or not a medical innovation.