Introduction - The acceptability and feasibility of HIV testing were analyzed in 27 emergency departments in the Île-de-France region as part of a study aimed at assessing the public health impact of routine HIV testing in the general population. Methods - For six consecutive weeks, emergency department staff, assisted as needed by study personnel, systematically offered adult patients HIV testing using rapid diagnostic tests (RDTs). Results - Of the 120,155 patients, 67,229 were eligible and 11,636 were tested (feasibility rate: 17.3%). Feasibility was higher in departments with a patient flow of fewer than 75 patients per day, when the offer was made by the emergency department team, and in departments located within Paris proper. Approximately two-thirds of those offered screening accepted it. Conclusion - Routine HIV screening is well accepted in emergency departments, and its feasibility varies from one center to another. Integrating screening into routine practice, when possible, appears more effective than assigning dedicated staff, and the obstacles to implementing such screening seem to be related more to patient flow and the organizational capacity of emergency departments than to public attitudes. (R.A.)