Operetta films (German: Operettenfilm) are a genre of musical films associated with, but not exclusive to, German language cinema. The genre began in the late 1920s, but its roots stretch back into the tradition of nineteenth century Viennese operettas.
Although some silent films had based their plots on stage operettas, the genre was largely a result of the switch from silent to sound films. The 1929 film Melody of the Heart, made by the German studio UFA, is credited as being the first "Operetta film". It had been intended as a silent film, but the dramatic arrival of sound forced its production to be switched. Its combination of music and dancing proved to be a successful formula, and it was followed by many similar films.
During the 1930s the trend spread to Britain, where a number of Operetta films were made (often in co-productions with German or Austrian studios), France and the United States. Many German émigré film-makers following the Nazi rise to power in 1933 were able to find work in other countries because of their experience in the genre. In the United States, a popular run of Operetta films were made starring Jeanette MacDonald and Nelson Eddy. In Britain the 1934 Richard Tauber film Blossom Time was a major hit, spawning a number of imitations.