"Juke" is a harmonica instrumental recorded by the Chicago bluesman Little Walter Jacobs in 1952. Although Little Walter had been recording sporadically for small Chicago labels over the previous five years, and had appeared on Muddy Waters' records for Chess Records since 1950, "Juke" was Little Walter's first hit, and it was the most important of his career. Due to the influence of Little Walter on blues harmonica, "Juke" is now considered a blues harmonica standard.

In May 1952, Little Walter had been a regular member of the Muddy Waters Band for at least three years. "Juke" was recorded on 12 May 1952 at the beginning (not the end, as commonly thought) of a recording session with Muddy Waters and his band, which at the time consisted of Waters and Jimmy Rogers on guitars, and Elga Edmunds on drums, in addition to Little Walter on harmonica. The originally released recording of "Juke" was the first completed take of the first song attempted at the first Little Walter session for Leonard Chess; the song was released as a single at the end of July on Chess's subsidiary label Checker Records The song was recorded by recording engineer Bill Putnam at his Universal Recorders studio at 111 E. Ontario St., on the near north side of Chicago. (Coincidentally, several years earlier Putnam had recorded one of the few other harmonica instrumentals ever to become a hit record, "Peg O' My Heart" by The Harmonicats.)

After recording two takes of "Juke" (the second, vastly different alternate take finally being issued for the first time over 40 years later), at the same session Little Walter recorded "Can't Hold On Much Longer", which took considerably more takes than "Juke" to complete. After the completion of Little Walter's recordings, Muddy Waters recorded his only song that day, "Please Have Mercy", backed by Little Walter and the band.

"Juke" is played as a swinging shuffle featuring a boogie-woogie guitar pattern, and is originally in the key of E; Walter played it in "second position" (cross harp) on a harmonica tuned to the key of A. "Juke" is a standard twelve-bar blues, set for the most part in the time signature of 4/4, but its time changes once to 3/4 and once to 2/4. "Juke" contains eight choruses.

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