Critical care medicine specialists (also called intensivists) are medical doctors who specialize in the care of people who are in an intensive care unit (ICU).

In some areas, when a person is very ill and has to spend time in an ICU, he or she is cared for by a critical care medicine specialist. After the person is transferred out of the ICU to a regular hospital unit, another doctor or health professional assumes care.

Most critical care specialists are respirologists (specializing in lung disease), cardiologists (specializing in heart disease), or neurologists (specializing in brain and nerve diseases). Critical care specialists may also first specialize in another area of medicine (such as anesthesiology, internal medicine, or pediatrics) and then hold a sub-specialist certificate in critical care medicine.

Critical care medicine specialists are certified by the Royal College of Physicians and Surgeons of Canada.