The Fantaisie in F minor, Op. 49, by Frédéric Chopin is a single-movement work for the piano, composed in 1841, when he was 31 years old.^[1] From Chopin's letters it is known that he used the name "fantasy" to show some sort of freedom from rules and give a Romantic expression.^[1] Frédéric Chopin continued the tradition of a self-contained movement in his Fantaisie.^[2] This Fantaisie is one of Chopin's longest pieces, and is considered one of his greatest works.^[3]

The autograph manuscript of the work is preserved in the National Library of Poland.

This work belongs to the Fantasy form, a composition free in form and inspiration.^[2] It begins with a solemn marching theme that eventually plunges into a passionate and virtuosic section, the transition marked poco a poco … doppio movimento, still with elements of marching, but more triumphant and positive in mood. About halfway through the piece occurs a slow and sombre chorale-like section in B major, before the previous section is restated. After a short, quiet and sweet statement followed by a final flourish the work ends in a plagal cadence in A-flat major, the relative key. This piece is 11–14 minutes long.