String Quartet in B-flat major may refer to: No. 4 of the String Quartets, Op. 33 (Haydn) No. 1 of the String Quartets, Op. 50 (Haydn) No. 3 of the String Quartets, Op. 64 (Haydn) No. 4 of the String Quartets, Op. 76 (Haydn) String Quartet No. 6 (Mozart) String Quartet No. 12 (Mozart) String Quartet No. 17 (Mozart) String Quartet No. 22 (Mozart) String Quartet No. 6 (Beethoven) String Quartet No. 13 (Beethoven) String Quartet No. 3 (Schubert) String Quartet No. 5 (Schubert) String Quartet No. 8 (Schubert) String Quartet No. 3 (Brahms) Quartet Movement in B-flat major (Tchaikovsky) String Quartet No. 2 (Dvořák) String Quartet in B-flat major (Sibelius) String Quartet No. 1 (Hill) String Quartet No. 5 (Shostakovich)