In May 1953, Tonga was assigned to the Western Pacific Region at the Sixth World Health Assembly ''without prejudice to any questions regarding sovereignty'' as an area. Tonga was under the British protectorate from 1900 to 4 June 1970, the same date its independence was restored. It joined WHO on 15 August 1975 as a Member State.

It was covered by the WHO Representative Office in the South Pacific since its establishment, and the WHO Country Liaison Officer was designated in March 1981.