 Serratus the flat block, performed under ultrasound guidance, is minimally invasive and easy to perform. It allows anesthesia and analgesia to an extended part of the anterolateral chest wall and the axilla. This regional anesthesia technique provides good analgesia during and after breast surgery, but remains to be evaluated; beyond perioperative analgesia, the benefit-risk, post operative rehabilitation, and the impact on ambulatory and on chronic pain are fundamental objectives. 