"Opus No. 1" is a popular song, composed in 1943 by Sy Oliver, with lyrics by Sid Garris. The tune is often titled Opus One, or Opus #1. It has become a standard song in the swing, jazz and big band repertoire.
The song was a big hit for the Tommy Dorsey Orchestra in 1944.
Read more about Opus No. 1: Recorded Versions