Specialized care that offers a service to those referred from secondary care for diagnosis or treatment, and which is not available in primary or secondary care. This kind of care is generally only available at national or international referral centers.
Tertiary care has become a common feature in certain specialties for rare conditions, or where the diagnostic or treatment facilities are scarce or require scarce combinations of resources, or which remain essentially the subject of research. These facilities are commonly found in medical schools and teaching hospitals.

Adapted from World Health Organization. Terminology. A glossary of technical terms on the economics and finance of health services. Internet. Accessed December 18, 2015.