In music, Op. 31 stands for Opus number 31. Compositions that are assigned this number include:
Alkan – Preludes, Op. 31 Barber – Summer Music Beethoven – Piano Sonata No. 16 Beethoven – Piano Sonata No. 17 Beethoven – Piano Sonata No. 18 Britten – Serenade for Tenor, Horn and Strings Chopin – Scherzo No. 2 Elgar – A Song of Flight Elgar – After Enescu – Vox Maris Farrenc – Piano Quintet No. 2 Górecki – Symphony No. 2 Gottschalk – Souvenir de Porto Rico Prokofiev – Tales of an Old Grandmother Rachmaninoff – Liturgy of St. John Chrysostom Saint-Saëns – Le rouet d'Omphale Schillings – Mona Lisa Schoenberg – Variations for Orchestra Schumann – 3 Gesänge Tchaikovsky – Marche slave Vierne – Vingt-quatre pièces en style libre