L.H.O.O.Q. (French pronunciation: [el aʃ o o ky]) is a work of art by Marcel Duchamp first conceived in 1919. The work is one of what Duchamp referred to as readymades, or more specifically an assisted ready-made. The readymade involves taking mundane, often utilitarian objects not generally considered to be art and transforming them, by adding to them, changing them, or (as in the case of his most famous work Fountain) simply renaming them and placing them in a gallery setting. In L.H.O.O.Q. the objet trouvé ("found object") is a cheap postcard reproduction of Leonardo da Vinci's Mona Lisa onto which Duchamp drew a moustache and beard in pencil and appended the title. Although many say it was pioneered by him, in 1883 Eugene Bataille created a Mona Lisa smoking a pipe, titled Le rire.
The name of the piece, L.H.O.O.Q., is a pun; the letters pronounced in French sound like "Elle a chaud au cul", "She is hot in the arse"; "avoir chaud au cul" is a vulgar expression implying that a woman has sexual restlessness. In a late interview (Schwarz 203), Duchamp gives a loose translation of L.H.O.O.Q. as "there is fire down below".
As was the case with a number of his readymades, Duchamp made multiple versions of L.H.O.O.Q. of differing sizes and in different media throughout his career, one of which, an unmodified black and white reproduction of the Mona Lisa mounted on card, is called L.H.O.O.Q. Shaved. The masculinized female introduces the theme of gender reversal, which was popular with Duchamp, who adopted his own female pseudonym, Rrose Sélavy, pronounced "Eros, c'est la vie" ("Eros, that's life").
Primary responses to L.H.O.O.Q. interpreted its meaning as being an attack on the iconic Mona Lisa and traditional art, thus promoting the Dadaist ideals.
According to Rhonda R. Shearer the apparent reproduction is in fact a copy partly modelled on Duchamp's own face.