SIC

Between 1970 and 2011, San Isidro Club won the Torneo de la URBA nineteen times. Twenty-seven titles overall, the most recent taken in 2023 alongside the Nacional de Clubes, a double that arrived nearly three decades after the club had first paired those two trophies in the same season, back in 1993 and 1994. South America came into view too, with three Campeonato Sudamericano titles in the second half of the 1980s.

Much of that record carries the name of Carlos "Veco" Villegas, who coached the club for nineteen seasons and left with thirteen championships to his name. Players who came through the club's ranks went on to be capped for Argentina, among them Juan Martín Hernández and Guido Petti.

No fixture matters more than the one against Club Atlético San Isidro. The Derby de San Isidro is treated as the most important club match in Argentine rugby, sharpened by the fact that SIC exists only because of CASI: eleven players suspended from that club broke away to form their own side on 14 December 1935. The white and light blue chosen at the time were CASI's own colours, kept as a mark of where the split had happened. Four years later, the new club took possession of a plot of land in Boulogne Sur Mer with a drainage ditch running through it, which members dug out and built up themselves — work remembered in the nickname El Zanjero, the ditch builder, that has stayed attached to the club since.