The organization of health care establishments and perioperative care are essential for ensuring the quality of care and safety of patients undergoing outpatient surgery. In order to correctly inventory these organizations and practices, in 2013–2014, the French society of anaesthesia and intensive care organized an extensive practical survey in French ambulatory surgery units entitled the “OPERA” study (Organisation periopératoire de l’anesthésie en chirurgie ambulatoire). From among all of the ambulatory surgery centres listed by the Agences régionales de santé (Regional health agencies, France), 206 public and private centres were randomly selected. A structural (typology, organization) survey and a medical-practice survey (focusing on the management of postoperative pain, nausea and vomiting as well as the prevention of venous thromboembolism) were collected and managed by a prospective audit of practices occurring on two randomly selected days. The latter was further accompanied by an additional audit specifically focussing on ten representative procedures: (1) stomatology surgery (third molar removal); (2) knee arthroscopy; (3) surgery of the abdominal wall (including inguinal hernia); (4) perianal surgery; (5) varicose vein surgery; (6) digestive laparoscopy–cholecystectomy; (7) breast surgery (tumourectomy); (8) uterine surgery; (9) hallux valgus and (10) hand surgery (excluding carpal tunnel). Over the 2 days of observation, 7382 patients were included comprising 2174 patients who underwent one of the procedures from the above list. The analysis of these data will provide an overview of the organization of health establishments, the modalities thus supported and compliance with standards.