Piano Concerto No. 4 in C minor (concerto pour piano en ut mineur), Op. 44 by Camille Saint-Saëns, is the composer's most structurally innovative piano concerto. In one sense it is like a four-movement symphony, but these are grouped in pairs. That is, the piece is divided into two parts, each of which combines two main movements (Part 1: I. Moderatetempo Theme and Variations in C Minor; II. Slower Theme and Variations in A-flat Major; Part 2: III. Scherzo in C Minor; IV. Finale in C Major). However, in each part there is a bridge-like transitional section, between the two main 'movements' - for example, a fugal Andante in part II functions as an interlude between the two main sections. The concerto begins with a gently mischievous chromatic subject, heard in dialogue between the strings and piano soloist, and continues in a creative thematic development similar to Saint-Saëns' Third Symphony. The composer demonstrates brilliant skill in employing the piano and orchestra almost equally. In the Andante, he moves to A-flat major with a chorale-like theme in the woodwinds (also strikingly similar to the tune of the Third Symphony's final section), and uses this as a platform on which to build a series of variations before bringing the movement to a quiet close. The Allegro vivace begins again in C minor as a high-spirited scherzo, using material foreshadowed in the first movement. 2/4 and 6/8 are playfully juxtaposed throughout. At one point, the piano boldly leads the orchestra in an energetic 6/8 theme in Eflat major. Eventually the orchestra moves to a lush Andante, recapitulating the Andante section from the first movement. Rather suddenly, the piano climbs up to a flurry of double octave trills, and a climactic trumpet fanfare, leads to the jubilant finale based on a hymn-like theme in triple time. The concerto concludes with the piano, in glittering cascades, guiding the orchestra to a fortissimo close.

The piano concerto was premièred in 1875 with the composer as the soloist. The concerto is dedicated to Antoine Door, a professor of piano at the Vienna Conservatory. It continues to be one of Saint-Saëns' most popular piano concertos, second only to the Piano Concerto No. 2 in G minor. This highly inventive work, along with many others, does much to refute the caricature of a purely reactionary Saint-Saëns.