The regencies of Luisa de Gusmao and Mariana of Austria were a milestone in the political and diplomatic history of the Iberian monarchies. Luísa governed in Portugal between 1656 and 1662, and Mariana was regent of Spain between 1665 and 1675. Over several years, both women had to face common problems. On the international stage, Luísa and Mariana served as true diplomatic queens, intervening in the warlike conflicts of their time and mediating in the conclusion of truces that allowed them to build both defensive and offensive coalitions. In this article I will carry out a comparative analysis of the political and diplomatic role of the regents with the intention of demonstrating how both queens contributed to the preservation of the territorial states of their sons, the kings Alfonso VI and Carlos II.