"It's Been A Long, Long Time" is a 1945 popular song that became a major hit at the end of World War II. The lyrics are written from the perspective of a person welcoming home his or her spouse or lover at the end of the war.

The music was written by Jule Styne, the lyrics by Sammy Cahn. A recording by Harry James with vocal by Kitty Kallen reached #1 on the Billboard Hot 100 chart on November 24, 1945. An alternate version by Bing Crosby accompanied by The Les Paul Trio was also working its way up the charts. It replaced the James' version at #1 on December 8, 1945. Crosby's lasted a week at #1, ousted by Sammy Kaye's "Chickery Chick." The Harry James recording then returned to the top spot on December 22 for another week.

In 1945 it was standard practice in the record industry for labels to release "competing" versions of hit songs. Other recordings of "It's Been A Long, Long Time" that charted in 1945 were recorded by Charlie Spivak & His Orchestra (with vocal by Irene Daye) and Stan Kenton & His Orchestra (vocal by June Christy).

Crosby's version features some memorable guitar by Les Paul, who recalled in an interview printed in Mojomagazine: "Bing was a sucker for guitar and that particular song was a case of you don't have to play a lot of notes, you just have to play the right notes."

The song quickly became a pop standard, with well received versions recorded by June Haver & Dan Dailey (1950), Perry Como (1956), Al Hibbler (1956), Peggy Lee(1959), Keely Smith (1959), Louis Armstrong (1964), and Tom Jones (1966). Frank Sinatra did not make a studio recording of the song, but sang a version on his radio show that has appeared on many Sinatra compilation albums.

Other artists who have recorded it include Guy Mitchell, Sammy Cahn, Shelley Fabares, Sammy Kaye, The Ink Spots, Tina Louise, Jimmy Roselli, Brook Benton, Rosemary Clooney, Chet Atkins (with Les Paul on their album Chester and Lester) and Star Trek: The Next Generation's Brent Spiner on his 1991 album, Ol' Yellow Eyes Is Back.