Sergei Prokofiev's Piano Sonata No. 4 in C minor, Op. 29 (1917) is a sonata composed for solo piano. It was first performed by the composer on April 17, 1918, in Petrograd. The work was dedicated to Prokoviev's good friend Maximilian Schmidthof, whose suicide in 1913 shocked and saddened the composer.
In his notes accompanying the full set of recordings of Prokofiev's sonatas by Boris Berman, David Fanning states the following:
Whether the restrained, even brooding quality of much of the Fourth Sonata relates in any direct way to Schmidthof's death is uncertain, but it is certainly striking that the first two movements both start gloomily in the piano's low register. Allegro molto sostenuto is the intriguing and apt marking for the first, in which a hesitant and uncertain mood prevails - the reverse of Prokofiev's usual self-confidence. The Andante assai second movement alternates between progressively more elaborate statements of the opening theme and a nostalgic lyrical episode reminiscent of a RachmaninovEtude-tableau; finally the two themes are heard in combination. With the rumbustious finale Prokofiev seems to be feeling himself again. But for all the gymnastics with which the main theme is varied there is less showiness in this essentially rather introvert work than in any of the other piano sonatas.