"I Didn't Know About You" is a 1944 song composed by Duke Ellington, with lyrics written by Bob Russell.
Alec Wilder wrote that it "works well as a song in [the] series of Ellington instrumentals with Russell lyrics. The main strain is the most melodic, vocally, of the three Russell wrote lyrics for. It was recorded by Ellington for Columbia records as a feature for alto saxophonist Johnny Hodges under the title of Sentimental Lady in December of 1959 but did not appear on the Blues In Orbit album until the CD era as a bonus track. Charlie Rouse and Thelonious Monk recorded it in 1966, also for Columbia, as I Didn't Know About You on Monk's Straight No Chaser album "