 Born in Santiago, he was the second son of Ramón Subercaseaux Vicuña and Amalia Errázuriz Urmeneta, both of them members of well-known and well-off families.And was the brother of Juan Subercaseaux.According to the Comité Olímpico de Chile, Luis Subercaseaux Errázuriz competed at the age of 13-14 in the 100, 400 and 800 metres although many Olympic historians dispute this claim and maintain that, although he was entered in these events, he did not take part in any race.