The film is a loose adaptation of the 1785 novel (first published in 1904) The 120 Days of Sodom by the Marquis de Sade, updating the story's setting to the World War II era.

The film explores themes of political corruption, consumerism, authoritarianism, nihilism, morality, capitalism, totalitarianism, sadism, sexuality, and fascism.

The film also contains frequent references to and several discussions of Friedrich Nietzsche's 1887 book On the Genealogy of Morality, Ezra Pound's poem The Cantos, and Marcel Proust's novel sequence In Search of Lost Time.

Because it depicts youths subjected to graphic violence, torture, sexual abuse, and murder, the film was controversial upon its release and has remained banned in many countries.

[4] The film is separated into four segments with intertitles, inspired by Dante's Divine Comedy:[5] In 1944, in the Republic of Salò, the fascist and Nazi-controlled portion of Italy, four wealthy men of power – the Duke, the Bishop, the Magistrate, and the President – agree to marry each other's daughters as the first step in a debauched ritual.

They recruit four teenage boys as collaborators (guards) in the Decima Flottiglia MAS and four young men (Blackshirt soldiers), called "studs", who are chosen because of their large penises and good looks.

Accompanying the libertines at the palace are four middle-aged prostitutes, also collaborators, whose job it is to orchestrate debauched interludes for the men, who sadistically exploit their victims.

Intrigued, the President moons several victims, as well as several collaborators including his favourite stud, Rinaldo, before prompting Efisio to perform anal sex on him while the Duke sings "Sul Ponte di perati".

Signora Vaccari uses a mannequin to demonstrate to the young men and women how to properly manually stimulate a penis only for Rinaldo to insult her for doing a poor job.

When one of the victims, Lamberto, refuses, the Magistrate whips him and tortures Susanna, the President's daughter, by tricking her into eating a slice of polenta containing nails.

Later, at a mock wedding reception for the Magistrate and Sergio, the victims are presented with a meal of human feces, which the studs, prostitutes and masters eat without question.

They are then taken outside and raped, tortured and murdered through methods such as branding, hanging, scalping, burning and having their tongues and eyes cut out, as each libertine takes his turn to watch as a voyeur.

Pasolini's writing collaborator Sergio Citti had originally been attached to direct the intended adaptation of the Marquis de Sade's The 120 Days of Sodom.

[7] During the creation of the first drafts of the script, Pasolini appealed to several of his usual collaborators, among them Citti, Claudio Masenza, Antonio Troisi and specially Pupi Avati.

[9] Salò is a toponymical metonymy for the Italian Social Republic (RSI) (because Mussolini ruled from this northern town rather than from Rome), which was a puppet state of Nazi Germany.

Laura Betti was also going to play Signora Vaccari, but also because of legal problems and prior commitments to Novecento declined the role, though she doubled the voice of Hélène Surgère in post-production.

[27] In-between working, the cast shared large meals of risotto and also had football games played against the crew of Bernardo Bertolucci's Novecento, which was being filmed nearby.

The crew of Novecento wore a purple shirt with phosphorescent bands to distract the opponents and had lined up, passing them off as engineers, two players from the youth team of Calcio Parma.

[citation needed] Like most Italian films of the time, Salò was shot MOS (without direct sound), with all dialogue and foley effects dubbed in post-production.

[32] Another final scene, discovered years later and which was only in the initial draft of the script, showed, after the torture's end, the four gentlemen walk out of the house and drawing conclusions about the morality of the whole affair.

The film remains banned in several countries and sparked numerous debates among critics and censors about whether or not it constituted pornography due to its nudity and graphic depiction of sexual acts.

It was first screened at the Old Compton Street Cinema Club in Soho, London in 1977, in an uncut form and without certification from BBFC secretary James Ferman; the premises were raided by the Metropolitan Police after a few days.

According to the Australian Classification Board media release, the DVD was passed due to "the inclusion of 176 minutes of additional material which provided a context to the feature film."

"[45] The majority opinion of the board stated that the inclusion of additional material on the DVD "facilitates wider consideration of the context of the film which results in the impact being no more than high.

The site's consensus reads, "Salò, or the 120 Days of Sodom will strike some viewers as irredeemably depraved, but its unflinching view of human cruelty makes it impossible to ignore.

"[62] TV Guide gave the film a mixed review awarding it a score of 2.5/4, stating, "despite moments of undeniably brilliant insight, is nearly unwatchable, extremely disturbing, and often literally nauseous".

[63] Upon the film's United States release, Vincent Canby of The New York Times wrote, "Salo is, I think, a perfect example of the kind of material that, theoretically, anyway, can be acceptable on paper but becomes so repugnant when visualized on the screen that it further dehumanizes the human spirit, which is supposed to be the artist's concern.

The filmic material of Salò is one that compacts celluloid and feces, in Pasolini's desire to burst the limits of cinema, via the anally resonant eye of the film lens.

"[35] Barber also notes that Pasolini's film reduces the extent of the storytelling sequences present in de Sade's The 120 Days of Sodom so that they "possess equal status" with the sadistic acts committed by the libertines.

[69] Dallas Marshall for Film Inquiry wrote in an article from 2021 that "Salò is his [Pasolini's] strongest diatribe against consumerism",[70] and other critics [71] have brought up that the film is to be seen as symbolism; a metaphor for the modern society, capitalism, and especially consumerism, i.e how "those in power can make people consume crap (ads, commercials, etc) and those of the people who resist die, and the majority passively obeys and goes along with the system, and a few will collaborate with the rulers".