At least 27 operas have been based on Romeo and Juliet. The earliest, Romeo und Julie in 1776, a Singspiel by Georg Benda, omits much of the action of the play and most of its characters, and has a happy ending. It is occasionally revived. The best-known is Gounod's 1867 Roméo et Juliette (libretto by Jules Barbier and Michel Carré), a critical triumph when first performed and frequently revived today. Bellini's I Capuleti e i Montecchi is also revived from time to time, but has sometimes been judged unfavourably because of its perceived liberties with Shakespeare; however, Bellini and his librettist, Felice Romani, worked from Italian sources—principally Romani's libretto for an opera by Nicola Vaccai—rather than directly adapting Shakespeare's play. Among later operas there is Heinrich Sutermeister's 1940 work Romeo und Julia.
Roméo et Juliette by Berlioz is a "symphonie dramatique", a large-scale work in three parts for mixed voices, chorus and orchestra, which premiered in 1839. Tchaikovsky's Romeo and Juliet Fantasy-Overture (1869, revised 1870 and 1880) is a 15-minute symphonic poem, containing the famous melody known as the "love theme". Tchaikovsky's device of repeating the same musical theme at the ball, in the balcony scene, in Juliet's bedroom and in the tomb has been used by subsequent directors: for example Nino Rota's love theme is used in a similar way in the 1968 film of the play, as is Des'ree's Kissing You in the 1996 film. Other classical composers influenced by the play include Henry Hugh Pearson (Romeo and Juliet, overture for orchestra, Op. 86), Svendsen (Romeo og Julie, 1876), Delius (A Village Romeo and Juliet, 1899–1901), Stenhammar (Romeo och Julia, 1922), and Kabalevsky (Incidental Music to Romeo and Juliet, Op. 56, 1956).