He is most famous for his operettas. The best known one is "The Merry Widow" (in German: "Die lustige Witwe") which is probably the most popular of all operettas. He also wrote sonatas, symphonic poems, marches, and a number of waltzes, some of which come from his famous operettas. Some of the songs from his operettas have become very well-known, especially "Vilja" from "The Merry Widow" and "You Are My Heart's Delight" ("Dein ist mein ganzes Herz") from "The Land of Smiles".