With the development of ambulatory surgery, there may be questions about the legal risk of this procedure. Indeed, the discharge of the patient from the hospital on the same day as the medical treatment raises the problem of monitoring and supervising potential complications, with a substantial delay in medical care, and the anaesthesiologists can be confronted with new areas of liability. This article specifies the French statutory and legal framework of the ambulatory surgery, and shows how the responsibility of the anaesthesiologist can be involved during patient care at all steps. The analysis of judicial precedent shows that the legal risk for the anaesthesiologist also exists in outpatient surgery. Surgery and anaesthesia are medical procedures involving a relatively high risk of damage for the patient. The damage can be attributed to malpractice from one or several health care professionals or to a medical complication (abnormal damage not related to malpractice and independent of past medical history of the patient). In the light of the ongoing and significant development in ambulatory surgery, there may be questions about the legal risk of this procedure. Indeed, the discharge of the patient from the hospital on the same day as the medical treatment raises the problem of monitoring and supervising potential complications, with a substantial delay in medical care. If the patient suffers any damage, the surgeon, the anaesthesiologist and in some cases, the hospital will have to answer in courts: the surgeon for the surgical procedure, the anaesthesiologist for the medical care and the hospital as the liable institution. After having specified the statutory framework of ambulatory surgery, we will see how the responsibility of the anaesthesiologist can be involved during patient care at all steps.