Eloísa Díaz Insunza was born on 25 June 1866 in Santiago, Chile. Her parents were Eulogio Díaz Varas and Carmela Insunza. Eloísa completed her requisite studies at Dolores Cabrera Martínez’s school, Isabel Le Brun de Pinochet’s school and at Instituto Nacional.
Eloísa enrolled in 1880 in Escuela de Medicina de la Universidad de Chile shortly after a law was enacted which allowed women to study at the university.
Eloísa graduated on 27 December 1886 and obtained her degree on 3 January 1887. Her thesis was named Breves observaciones sobre la aparición de la pubertad en la mujer chilena y las predisposiciones patológicas del sexo (English: Brief observations on the apparition of puberty in Chilean women and their pathological predispositions about sex).
Eloísa became the first woman in South America to graduate and earn her medical license.
Eloísa began working at San Borja Hospital in January 1891. She worked as a teacher and physician in Escuela Normal from 1889 until 1897. Eloísa became the School Medic Supervisor of Santiago in 1898 and was promoted to School Medic Supervisor of Chile. She held this position for more than 30 years.
As a philanthropist, Eloísa founded several kindergartens, polyclinics for the poor and school camps.
In 1910, Eloísa participated in the Hygiene and Medicine International Scientific Congress in Buenos Aires, where she was named “Illustrious Woman of America”. She was named Director of the School Medical Service of Chile in 1911, where she implemented school breakfasts and mass vaccination of students, as well as campaigns to combat alcoholism, rickets and tuberculosis.
In 1919, together with Celinda Arregui, Beatriz Letelier, Hayra Guerrero de Sommerville, Isaura Dinator, Juana de Aguirre Cerda, Carmela de Laso and Fresia Escobar, Eloísa founded the National Council of Women of Chile “which actively participated in the defense of women’s rights”.
Eloísa retired in 1925. In 1950, Eloísa was taken ill and admitted to the San Vicente de Paúl Hospital, where she died on November 1, at the age of 84.