Résumé : Chemoreceptors are able to detect both hypoxemia and hypercapnia. They respond by increasing ventilation and the activity of the sympathetic nervous system. This loop is a key mechanism able to maintain homeostasis. This reflex is inhibited by pulmonary afferents stretch and by baroreflex activation. Dysfunction of the chemoreflex per se or of inhibitory influences is largely involved in the pathophysiology of various cardiovascular diseases as well as in their prognosis. These structures could thus also be considered as therapeutic targets for new pharmacological agents.