Hypoxemia is the most life threatening condition experienced in the intensive care units. The health care professionals should be well versed with the management of hypoxemia.There are several oxygen therapy devices used starting with Low flow systems ,High flow sytems and reservoir system . Each oxygen therapy device has its own pros and cons and the clinician choses the best device based upon the experience as well as evidence based practise. Recently a device known as High Flow Nasal Cannula oxygen Therapy is been used to improve oxygenation in critically ill patients. High Flow nasal cannula has control over three parametres such as flow, Fio2, and temperature. All these parameters are important for the patient where high flow oxygen is going through the nasal cannula .HFNC is used in the conditions such as early ARDS, Hypoxemia ,acute COPD , postextubation, ,sleep related disorders , acute heart diseases . Howevar more studies should be conducted in patients with High Flow nasal cannula oxygen therapy to use it more frequently in intensive care units.