Pain concerns more than 50% of the children cared in the emergency unit. After evaluation, it has to be cured with drugs adapted to its level and its origin. Residual pain needs therapeutic adjustment. The goal is to allow the child to restart his activities. A preventive sedation analgesia is necessary when a painful exam is to be performed, either for diagnosis or therapeutic purpose. For this goal ideal analgesics, either for monotherapy or associated, are easily and painlessly administered. They have rapid onset of action, brief half-life, predictable, effective analgesic properties without side effects and they are quickly reversible. These drugs do not exist and every sedation procedure has a risk of hypoxemia. With the human and equipment's investment an emergency department should be able to ensure that procedures are performed in children under sedation with a standard of safety that is similar to general anaesthesia. The main drawback in a well-organised system should be a significant children's rate for which general anaesthesia is preferred.