Felix Mendelssohn wrote six numbered string quartets which were published during his lifetime: Portrait of Mendelssohn by the English miniaturist James Warren Childe (1778-1862), 1839 Jakob Ludwig Felix Mendelssohn Bartholdy, born and generally known as Felix Mendelssohn (February 3, 1809 – November 4, 1847) was a German composer and conductor of the early Romantic period. ... The resident string quartet of the Library of Congress in 1963 A string quartet is a musical ensemble of four string instruments—usually two violins, a viola and cello—or a piece written to be performed by such a group. ...

• String Quartet No. 1 in E flat major, Op. 12 composed in 1829
• String Quartet No. 2 in A minor, Op. 13 composed in 1827
• String Quartet No. 3 in D major, Op. 44, No. 1 composed in 1838
• String Quartet No. 4 in E minor, Op. 44, No. 2 composed in 1837
• String Quartet No. 5 in E flat major, Op. 44, No. 3 composed in 1838
• String Quartet No. 6 in F minor, Op. 80 composed in 1847

Mendelssohn also wrote another quartet in E flat major at the age of 14, just after he had composed his 13 string symphonies. However, the quartet was never published in his lifetime and so was never assigned an opus number. The String Quartet No. ... Opus, from the Latin word opus meaning work, is usually used in the sense of a work of art. In this sense the plural of opus, opera, is used to refer to the genre of music drama. ...

Mendelssohn's first two numbered quartets were published out of order, whilst his next three quartets were published together as Op. 44 and were all dedicated to Crown Prince Gustavus of Sweden.

Mendelssohn's final string quartet was composed after the death of his sister, which caused to devastating blow to Mendelssohn. The quartet was also his last major work, as he died only two months after its completion. The piece was published shortly before his death along with a set of four pieces for string quartet also composed in his final years.