Intensive Care Unit (ICU), or sometimes known as Intensive Therapy Unit or Intensive Treatment Unit (ITU), or Critical Care Unit (CCU), is a unique department that provides intensive treatment medicine and comprehensive care for critically ill patients.

The ICUs mainly serve patients with severe and life-threatening illnesses or injuries. Such patients are usually required to be monitored continuously by a team of committed specialists and medical staff. The patients also need constant support from specialized equipment and medication to stabilize their body function.

The ICUs tend to have a higher ratio of staff to patient as well as the access to advanced medical resources and equipment which are not commonly available elsewhere. Meanwhile, common conditions treated in the ICUs include Acute or Adult Respiratory Distress Syndrome (ARDS), Multiple Organ Failure (MOF), sepsis and trauma.

The patients may be shifted to an ICU from Accident and Emergency (A&E) Department if required or, from Operation Theatre (OT) immediately after a surgery if the surgery is invasive which may cause the patient to have high risk of complications or, from a normal ward if they rapidly deteriorate.