In an anesthesiologist's practice, except the occurrence of clinical death on the operating table a long-term complete suppression of the electrical activity of the brain may arise only from the medical staff's crude error when administering intravenous anesthetics from the unlikely breakage of the anesthesia apparatus vaporizer. However, the authors assert that such a phenomenon may develop during general anesthesia using propofol given in its usual doses. Clinical examples are given. Whether the depth of general anesthesia should be controlled by the principle of feedback, by making neurophysiological monitoring is discussed.