Luis Buñuel said that many of Tristana's idiosyncrasies, including her habit of asking people to choose between nearly identical objects, was based on the director's sister's similar habits.
Upon receiving an Academy Award nomination for this film, director Luis Buñuel said "nothing would disgust me more, morally, than to win an oscar." The Academy ultimately selected Investigation of a Citizen Above Suspicion (1970) as the winner of the Best Foreign Language Film category and spared Bunuel further moral indignation.
Luis Buñuel stated that this film was twenty years in the making. He first considered making the film in 1950, during his Mexican period. The project never materialized, and efforts to make the film in Buñuel's native Spain were twice quashed by censorship issues before it finally was given the green light in late 1969.
Luis Buñuel was a big fan of the works of Benito Pérez Galdós, the author of the novel which served as the source material for this film. However, Buñuel was quite critical of this particular Galdós novel, which shares the same name as this film. Buñuel found the novel to be kitschy, predictable, and among the author's worst works. Nonetheless, the director believed that it would make an excellent film translation, and worked to get the film produced for many years.
Luis Buñuel made changes to the original novel by Benito Pérez Galdós to make the film more personal. For instance, he moved the setting from Madrid to his one-time home of Toledo. As well, he changed the original timeframe from the late 1800s to the late 1920s when he, himself, was a young man.