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]

• David Fallows. "Formes Fixes", Grove Music Online, ed. L. Macy (accessed September 16, 2006), grovemusic.com Archived 2008-05-16 at the Wayback Machine (subscription access).

• Wilkins, Nigel (1968). "The Post-Machaut Generation of Poet-Musicians". Nottingham Medieval Studies. 12. Turnhout, Belgium: Brepols: 40–84. doi:10.1484/J.NMS.3.38.