Gallardo was born in Buenos Aires to an upper class family with extensive agricultural property. She became an astute observer and critic of the Argentine aristocracy, much along the lines of Charlotte Brontë. She was Bartolomé Mitre's great-great-granddaughter.
She was married twice, first to Luis Pico Estrada and then to H. A. Murena. Gallardo began publishing in 1958. In addition to her numerous newspaper columns and essays, she published five novels, a collection of short stories, several children’s books, and a number of travelogues. She contributed to the magazines Primera Plana, Panorama and Confirmado among others. She is quoted as often saying, "Writing is an absurd and heroic activity."
Greatly affected by the death of her second husband in 1975, she moved with her children to La Cumbre, Córdoba Province, to a house that was provided by the writer Manuel Mujica Láinez. Then in 1979, moved to Barcelona, Spain where she wrote The Rose in the Wind (La Rosa en el Viento), her last book. She continued her travels in Switzerland and Italy, but did not finish any more works. Upon her return to Argentina she died of an asthma attack in Buenos Aires at age 56. She left notes on a planned biography of the Jewish intellectual and Carmelite nun, Edith Stein, who had been killed at the Auschwitz concentration camp in 1942.
Enero ("January ")(1958) was her first novel and details the intensely private world of an adolescent farmworker. It is written in a deliberately ambiguous way to reflect the confusions that face the heroine as she deals with her unwanted pregnancy, the product of her being raped.
El País del Humo ("Country of the Smoke")(1977) was a collection of her short stories, and literary sketches that showed more of her fantastical side that had formerly appeared more in her children’s books. Some of them have been considered outright science fiction.
- Brizuela, Leopoldo (4 January 2004) "Escrito en las llamas" ("Writing in the Flames") Página/12 Buenos Aires, Argentina in Spanish
- Flores, Angel (1992) "Sara Gallardo" Spanish American Authors: The Twentieth Century H. W, Wilson Company, New York, p. 333, ISBN 0-8242-0806-4
- "Sara Gallardo" El Broli Argentino
- "Escribir es un oficio absurdo y heroico" "Sara Gallardo" El Broli Argentino
- Gallardo, Sara (1958) Enero Editorial Sudamericana, Buenos Aires, OCLC 4977668, reprinted in numerous editions
- Gallardo, Sara (1977) El País del Humo Editorial Sudamericana, Buenos Aires, OCLC 3987620
- "Index to Non-English Language Women SF Writers" Feminist Science Fiction, Fantasy & Utopia
- Flores, Angel (1992) "Sara Gallardo" Spanish American Authors: The Twentieth Century H. W. Wilson Company, New York, pp. 333–335, ISBN 0-8242-0806-4
- Marting, Diane E. (Ed.) (1990) "Gallardo, Sara (1931-1988)" Spanish American Women Writers: A bio-bibliographical source book" Greenwood Press, New York, ISBN 0-313-25194-0
- Pollastri, Laura (1980) Fantasía y realismo mágico en dos cuentos de El País del humo, de Sara Gallardo Dirección General de Cultura, Departamento de Literatura Argentina, Tucumán OCLC 65651831 - a seven-page paper presented at the Congreso Nacional de Literatura Argentina, held in Horco Molle, Aug. 14-17, 1980, in Spanish.
- "Narrativa Breve Completa de Sara Gallardo" La Basica Online ("Short Narrative on the Complete Works of Sara Gallardo") in Spanish
- "Sara Gallardo" El Broli Argentino in Spanish
- Brizuela, Leopoldo (27 September 2005) "Sara Gallardo en el país del humo" La Nación in Spanish