Viridiana (Pinal) is a novitiate nun who is about to take her vows. Since she is about to be shut up within a convent forever, the Mother Superior urges her to pay a last visit to her only living relative, her uncle Don Jaime. She barely knows him but he paid for her education, so she reluctantly complies.
Viridiana travels to her uncle's estate and, after meeting him, tells Don Jaime that she feels nothing for him and that it's too late for them to have a relationship. Don Jaime for his part is shocked at Viridiana's strong resemblance to his late wife, who died of a heart attack on their wedding night. Don Jaime cajoles Viridiana into putting on his wife's wedding dress, then begs her to stay at the mansion and marry him. A horrified Viridiana refuses, but Don Jaime has drugged her coffee.
Tragedy ensues. Viridiana meets Don Jaime's long-lost son Jorge played by Francisco Rabal who was actually only 9 years younger than Ferdando Rey. Viridiana seeks to do good deeds, and turns an outbuilding of the estate into a dormitory for the local homeless—but that ends in disaster as well.
- Attempted Rape: The second time Viridiana is nearly raped, she's saved only by one bum, who was hoping for his own turn, crashing a fireplace shovel over the first rapist's head, after being bribed by Jorge.
- Belief Makes You Stupid: It is safe to say that the film takes a dim view of Catholic piety. Viridiana's do-gooder instincts lead her to invite a bunch of dirty homeless people to the mansion; they trash the place and nearly rape her. The final scene shows Viridiana having apparently cast her religion behind, content to live with Jorge, while her crown of thorns burns in the yard.
- Cat Fight: Two of the female bums get into the standard hair-pulling Cat Fight as the party gets more drunken and disorganized. Subverted in that they are dirty, gross homeless people, as opposed to the standard Fanservice Cat Fight.
- Creepy Crossdresser: Don Jaime puts on his dead wife's shoes at one point. Later, one of the drunken bums dons part of the dead wife's wedding dress, and does an unsettling little dance.
- Disappeared Dad: Don Jaime explains that he never had anything to do with his illegitimate son Jorge because his wife wouldn't have liked it. This doesn't stop him from leaving the estate to Jorge in his will.
- Driven to Suicide: Don Jaime hangs himself after Viridiana rejects him.
- Dude, She's Like in a Coma: Don Jaime paws at Viridiana's breasts after drugging her.
- Identical Stranger: Viridiana is a carbon copy of Don Jaime's long-deceased wife.
- Gratuitous English: The recording of "Messiah" that the bums listen to is in English, as is the pop song that Jorge plays during the final scene.
- Grievous Bottley Harm: One of the bums smashes a wine bottle over Jorge's head as he's trying to save Viridiana from being raped. He is conscious and no worse for wear a few short moments later.
- Humans Are Bastards: Heavily implied throughout the whole movie, with the subtext being that any attempt to help them or do good will most likely get you taken advantage of or worse.
- I Love the Dead: Implied when Don Jaime takes Viridiana (drugged unconscious, still wearing the wedding dress) and lays her out on the bed. He arranges her carefully, perfectly straight, her hands clasped on her chest as one would arrange a corpse. Then he starts pawing her.
- Kissing Cousins: One of the themes. Don Jaime asks his niece to marry him. Later, Jorge his clearly attracted to his first cousin, and the ending implies that they are together.
- "Last Supper" Steal: The most famous shot has all the dirty, profane beggars befouling the dining room of the main house posing in an exact duplicate of The Last Supper. It was stuff like this that got the film in trouble with the Catholic Church and Spanish censors.
- Letting Her Hair Down: Viridiana is a changed woman after she is nearly raped for a second time, her instinct for charity having blown up in her face. Her hair, pinned up throughout the movie, is cascading around her shoulders as she seemingly rejects good works and accepts a life with Don Jaime and Ramona.
- Near-Rape Experience: Don Jaime lays a drugged Viridiana out on the bed, undoes her dress, fondles her breasts—then flees from the room.
- No Good Deed Goes Unpunished: Viridiana reluctantly indulges her uncle's desire to see her one time before she joins the convent. He drugs her and nearly rapes her. Later, she turns the estate into a homeless shelter. The homeless bums trash the place, and she again nearly gets raped.
- Nun Too Holy: Viridiana tries to be Mother Teresa, but is secretly Prideful of her Good Works. She's really more misinformed and naive than 'bad', but she screws it up magnificently nevertheless.
- A Party, Also Known as an Orgy: The bums sneak their way into the main house and decide to have dinner in the fancy dining room. It dissolves into a drunken orgy that includes sex behind the sofa.
- Polyamory: After Letting Her Hair Down, Viridiana, who is obviously very changed by her experiences, enters the bedroom and finds Jorge and his lover Ramona. She sits down at a table with them. Jorge, who has a deck of cards, starts dealing, looks at Viridiana, and says "When I first saw you, I knew that we would end up playing cards."
- Replacement Goldfish: Seems to be Don Jaime's motivation, as a portrait reveals that his late wife looked exactly like Viridiana.
- Sexy Discretion Shot: The camera cuts away as Jorge is seducing Ramona the maid.
- She's Got Legs: The film takes care to show Viridiana's very, very nice legs as she changes from her nun's habit into her nightclothes.
- Sleepwalking: Viridiana does this after arriving at Don Jaime's house. She scoops up some ashes from the fireplace, and dumps them in Don Jaime's bed.
- Slipping a Mickey: Viridiana does not much care for Don Jaime's suggestion that she marry him. So Don Jaime has his maid Ramona drug her coffee.
- Standard Snippet: George Frederic Handel's "Messiah" ("hallelujah, hallelujah, hal-le-lu-jah") plays over the opening credits and again during the drunken party near the end.
- Younger than They Look: Don Jaime is played by Fernando Rey who is actually below 45 here. The actor is also only 9 years older than Francisco Rabal playing Jorge. Anyway 45 was an age when the Spanish bachelors were still eligible to marry young girls. However Jaime looks like a nearly old man.
- Your Mom: One of the bums at the party asks the blind bum how he can scratch an itch if he can't see where it is. The blind bum says "Tell Zequiel that when I get an itch, I'll get his mother to scratch it for me."