The Toy Symphony (full title: Cassation in G major for toys, 2 oboes, 2 horns, strings and continuo) is a musical work with parts for toy instruments.
It was long reputed to be the work of Joseph Haydn, but later scholarship suggested that it was actually written by Leopold Mozart. Its authorship is still disputed, however, and other composers have been proposed as the symphony's true author, including Joseph Haydn's younger brother Michael Haydn, who purportedly contributed movements to the work.
Recent research on a newly found manuscript suggests the Austrian benedictine monk Edmund Angerer (1740–1794) to be the author. If Angerer's manuscript is the original, the Toy Symphony was originally written not in G but rather in C. These findings, however, are disputed among scholars. There is reason to believe that the true composer will likely never be known, in whole or in part, given its confused origins and the paucity of related manuscript sources.