Oxygen adiministration for both medical and traumatic emergencies is regarded as an essential component of resuscitation. However, many recent studies suggest that the use of oxygen should be more restrictive. Detrimental effects of normobaric oxygen therapy in patients suffering from hypercapnic respiratory diseases have been demonstrated, especially because of the suppression of the hypoxic drive. Apart from this particular situation, correction of hypoxemia is still a widely accepted treatment target, although there is growing evidence that hyperoxemia could be harmful in acute coronary syndromes and cardio-respiratory arrests. In other pathologies, such as stroke or hemorragic shock, the situation is still unclear, and further studies are needed to clarify the situation. Generally speaking, oxygen therapy should from now on be goal-directed, and early monitoring of both pulse oximetry and arterial blood gases is advised.