The author presents his personal evaluation of the nature of awareness during anaesthesia. This is primarily based on the actual cases described in the literature to date. When a patient feels pain or discomfort ( and also hears ), this must be clearly interpreted as inadequate anaesthesia. In the absence of pain or discomfort and when the patient is apparently “properly anaesthetised,” awareness has consistently been characterized by the persistence of hearing. The level of anaesthesia fluctuates during an anaesthetic. The patient may thus enter a “zone of subconscious attention” when there is a risk that he may hear something. This risk will be greater if the patient is worried about his condition (increased subconscious activity). Conversation during the operation should always be discreet, both in topic and sound level. Earplugs are of value, especially when the operation demands very light anaesthesia, or higher oxygen percentage ( e.g. Caesarean sections and poor risk cases ). Hypnosis is of value in research on awareness and possibly in the treatment by hypnoanalysis of a patient who has been adversely affected by the subconscious memory of events during surgery. Subconscious traumata should be regarded as “the invisible scars of surgery.” They may have a profound effect on the patient’s psyche and future life. It is the anaesthetist’s duty always to ensure oblivion as well as analgesia during surgery.