The Secretary General of the Union of South American Nations is the legal representative of the Secretariat of the Union of South American Nations (USAN).

The position was established by the UNASUR Constitutive Treaty and the first Secretary General was designated on 4 May 2010.

[1] The Secretary General exercises the legal representation of the UNASUR Secretariat.

The officials selection for the latter requires an equitative representation between UNASUR Member States.

It also requires an equitative representation, as much as possible, along gender, language and ethnic criteria.