The Gran Premio 25 de Mayo (previously Premio San Isidro, Gran Premio San Isidro, Gran Premio Internacional 25 de Mayo) is a Group 1 horse race run at Hipódromo de San Isidro, in Buenos Aires, Argentina.
Since 2012, the winner receives a “Win and You're In” berth into the Breeders' Cup Turf through the international Breeders' Cup Challenge.
It became the Gran Premio San Isidro in 1951 and was renamed the Gran Premio 25 de Mayo in 1959, although it ran as the Gran Premio Internacional 25 de Mayo 1960–1963.
[2] Until 1959, the Gran Premio 25 de Mayo was run at a distance of 3000 meters; this was reduced to its current length of 2500 meters in 1960.
From 1951 until its distance reduction, the fastest time run was 3:051⁄5 by Yatasto in 1953.