Wolfgang Amadeus Mozart's Clarinet Quintet, K. 581, was written in 1789 for the clarinetist Anton Stadler.

[3] It received its premiere on 22 December of the same year, in one of the four annual Vienna performances of the Tonkünstler-Societät, an organization that existed to fund pensions for widows and orphans of musicians.

It has beautiful moving lines in all of the parts and in the second half there is a virtuoso run that is passed throughout the strings, based on material from the second section of the exposition.

The second movement opens with a six-bar transition in place of a central development section, which opposes a first section consisting mostly of a clarinet melody over muted strings against a second group of themes in which – as in the first movement – several upward runs of scales are given to the first violin, alternating with brief phrases of clarinet melody.

In the last few bars of the movement, more chromatic than the rest, the scales turn into triplet arpeggios traded between the strings under the closing clarinet phrases.

A score fragment exists for a second (although possibly written first) clarinet quintet in B-flat major, of which a complete exposition survives.

[8] It is possible that Mozart completed the movement, as the score continues into the development section on the last surviving page.

The fragment in A, Anhang 88, for basset clarinet in A and string quartet may originally have been intended as the fourth movement of KV 581.

Several musicians have made completions including Otto Bach (1870), Robert Levin (2012), and Craig Hill (2022).

In "Goodbye, Farewell and Amen", the final episode of the American television series M*A*S*H, Charles Winchester learns that five Chinese soldiers who surrendered to him are musicians, one of whom plays a theme from the Clarinet Quintet, and Winchester proceeds to teach them the entire piece.