In music, Op. 51 stands for Opus number 51. Compositions that are assigned this number include:
Arnold – Tam O'Shanter Overture Beethoven – Two rondos for piano Brahms – Two String Quartets Chopin – Impromptu No. 3 Dvořák – String Quartet No. 10 Elgar – The Kingdom Fibich – Šárka Holst – A Choral Fantasia MacDowell – Woodland Sketches Prokofiev – On the Dnieper Schubert – Three Marches Militaires Schumann – Lieder und Gesänge volume II (5 songs) Scriabin – Prelude in A minor, Op. 51, No. 2 Sibelius – Belshazzar's Feast (), theatre score and suite (1906, arranged 1907) Tchaikovsky – 6 Pieces for solo piano