Il segreto di Susanna is an intermezzo in one act by Ermanno Wolf-Ferrari to an Italian libretto by Enrico Golisciani. The opera premiered in 1909 and is the most frequently performed of all of Wolf-Ferrari's works. The overture of the work has become a well known concert piece.The opera tell's the story of a husband who suspects his wife is having an affair after discovering she smells like cigarettes; only later to discover that her secret is that she is a smoker. Musicologist John C.G. Waterhouse, wrote the following: "Il segreto di Susanna owes its success partly to its disarming simplicity. Lasting barely 45 minutes, with only two singing characters, it is conveniently cheap to produce; and the slender but distinctive idea of the libretto, combined with the elegant if rather miscellaneous charm of the music, has an obvious appeal which even subsequent cancer research has not seriously undermined."

Ermanno Wolf-Ferrari was an Italian composer and teacher. He is best known for his comic operas such as Il segreto di Susanna (1909). A number of his works were based on plays by Carlo Goldoni, including Le donne curiose (1903), I quatro rusteghi (1906) and Il campiello (1936).