In music, Op. 42 stands for Opus number 42. Compositions that are assigned this number include:
Arnold – Homage to the Queen Britten – Saint Nicolas Bruch – Romance in A minor Busoni – Berceuse élégiaque Chopin – Waltz in A-flat major, Op. 42 Elgar – Diarmuid and Grania Glière – Symphony No. 3 Haydn – String Quartet in D Minor, Op. 42 Holst – At the Boar's Head Ippolitov-Ivanov – Caucasian Sketches, Suite No. 2 Mendelssohn – Psalm 42 Nielsen – Fynsk Foraar Rachmaninoff – Variations on a Theme of Corelli Rautavaara – Études Schumann – Frauenliebe und -leben Shostakovich – Five Fragments Tchaikovsky – Souvenir d'un lieu cher Widor – Symphony for Organ No. 5 Widor – Symphony for Organ No. 6