"Things Ain't What They Used to Be" is a 1942 jazz standard composed by Mercer Ellington.
In 1941 there was a strike against the American Society of Composers, Authors and Publishers, of which Duke Ellington was a member. Because of the strike he could not air his songs on the radio. Instead, he used songs written by his son Mercer and pianist Billy Strayhorn. Strayhorn's compositions of this time include "Take the 'A' Train", "Chelsea Bridge" and "Day Dream", and Mercer wrote "Things Ain't What They Used to Be", "Blue Serge" and "Moon Mist".
Jazz musician and historian Chris Tyle argues that most likely Mercer Ellington came up with the melody and his father then arranged the song for the band. The song is most often played as an instrumental. Lyrics were written by Ted Persons.
In 1990, guitarist Larry Coryell covered the song from his album "Dragon Gate."