The Institutional Security Bureau (Portuguese: Gabinete de Segurança Institucional da Presidência da República, GSI; English: Institutional Security Bureau of the Presidency of the Republic, ISB) is an executive cabinet office of the federal government of Brazil responsible for providing direct assistance at a moment's notice to the President on matters of national security and defense policy.

It is currently headed by retired general Marcos Antonio Amaro dos Santos.

[2] Created by Provisional Measure (MP) No.

1911-10 of 24 September 1999 by President Fernando Henrique Cardoso.

The existence of a body responsible for institutional security is not new in Brazilian history, having been the responsibility of multiple government agencies prior to the creation of the Institutional Security Bureau: