The formes fixes (French: [fɔʁm fiks]; singular: forme fixe, "fixed form") are the three 14th- and 15th-century French poetic forms: the ballade, rondeau, and virelai. Each was also a musical form, generally a chanson, and all consisted of a complex pattern of repetition of verses and a refrain with musical content in two main sections.

All three forms can be found in 13th-century sources, but a 15th-century source gives Philippe de Vitry as their first composer while the first comprehensive repertory of these forms was written by Guillaume de Machaut.^[1] The formes fixes stopped being used in music around the end of the 15th century, although their influence continued (in poetry they, especially the rondeau, continued to be used^[1]).

Sometimes forms from other countries and periods are referred to as formes fixes. These include the Italian 14th-century madrigal and later ballata and barzelletta, the German bar form, Spanish 13th-century cantiga, and the later canción, and villancico.^[1]