WHO
Which countries are in WHO? 193 member countries in the Magna Factbook, ranked by Magna Power.
Last updated: October 2026
WHO — the World Health Organization — is the UN’s specialized agency for health. Its Constitution was adopted on 22 July 1946 and entered into force on 7 April 1948, now marked as World Health Day. It defines health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”
Headquartered in Geneva, WHO counts 193 member states. It is the directing and coordinating authority on international health work.
The World Health Assembly, where every member sits, meets each May and sets policy. A 34-member Executive Board prepares its work. A Director-General runs the secretariat: Tedros Adhanom Ghebreyesus of Ethiopia has held the post since 2017.
Six regional offices — Africa, the Americas (PAHO), Eastern Mediterranean, Europe, South-East Asia and Western Pacific — run programmes close to the ground.
WHO sets the International Health Regulations, runs the global immunization programme (EPI, since 1974), publishes the Model List of Essential Medicines, and declares Public Health Emergencies of International Concern. Its greatest triumph was the eradication of smallpox, certified in 1980; polio is near eradication.
- WHO, who.int — Constitution, members, regional offices.
- WHO Constitution, 22 July 1946.
- International Health Regulations (2005).
- Declaration of Alma-Ata, 1978 — primary health care.