In music, Op. 28 stands for Opus number 28. Compositions that are assigned this number include:

Beethoven – Piano Sonata No. 15

Britten – A Ceremony of Carols

Chopin – Preludes, Op. 28

Danzi – Horn Sonata No. 1

Elgar – Organ Sonata

Enescu – Impressions d'enfance

Ginastera – Piano Concerto No. 1

Holbrooke – Horn Trio

Holst – First Suite in E-flat for Military Band

Korngold – Die Kathrin

Myaskovsky – Symphony No. 9

Prokofiev – Piano Sonata No. 3

Rachmaninoff – Piano Sonata No. 1

Ries – Piano Trio, Op. 28

Saint-Saëns – Introduction and Rondo Capriccioso

Schmitt – Reflets d'Allemagne

Schumann – Three Romances for piano

Scriabin – Fantaisie in B minor

Strauss – Till Eulenspiegel's Merry Pranks

Szymanowski – Nocturne and Tarantella

Vierne – Organ Symphony No. 3

Waterhouse – Three Pieces for Solo Cello

Webern – String Quartet

Op. 28