"Day In, Day Out" is a popular song with music by Rube Bloom and lyrics by Johnny Mercer and published in 1939.
According to Alec Wilder the song, 56 measures long, has a wonderful, soaring melodic line, free from pretentiousness, but full of passion and intensity which is superbly supported by the lyrics. Although the catch phrase "day in—day out" sounds like a dull routine, Mercer uses exotic images to contrast with the boring sound of the phrase.
The song has been recorded by numerous artists.