The String Quartet No. 16 in F major, op. 135, by Ludwig van Beethoven was written in October 1826 and was the last substantial work he finished. Only the last movement of the Quartet op. 130, written as a replacement for the Große Fuge, was written later. The op. 135 quartet was premiered by the Schuppanzigh Quartet in March 1828.

The work is on a smaller scale than his other late quartets. For the third movement, Beethoven used variation techniques; he also did this in the second movement of his Quartet op. 127. Under the introductory slow chords in the last movement Beethoven wrote in the manuscript "Muß es sein?" (Must it be?) to which he responds, with the faster main theme of the movement, "Es muß sein!" (It must be!). The whole movement is headed "Der schwer gefaßte Entschluß" ("The Difficult Decision").

It is in four movements:

Notes

1. ^ Steinberg, Michael (1994). Robert Winter, Robert Martin, ed. The Beethoven Quartet Companion. University of California Press. p. 274. ISBN 0-520-08211-7. 
2. ^ Bernard Jacobson. "Beethoven: The Complete String Quartets." EMI 5736062. CD liner notes, 24.