Anesthesia awareness, or "unintended intra-operative awareness" occurs during general anesthesia, when a patient has not had enough general anesthetic or analgesic to prevent consciousness.

Awareness occurs in 20,000-40,000 patients out of every 20 million US annual surgeries every year when patients have anesthesia that is inadequate to keep them unconscious during an operation. In this situation, the patient may feel the pain or pressure of surgery, hear conversations, or feel as if they cannot breathe. The patient may be unable to communicate any distress because they have been given a paralytic/muscle relaxant. If anesthesia awareness does occur about 40% feel the pain of the operation, 92% experience panic/anxiety and 70% experience lasting psychological symptoms.

In some cases, post traumatic stress disorder (PTSD) may arise after intraoperative awareness, causing the patient to require counseling for an extended period.