As in several of Haydn's other Op. 50 quartets, this final installment in the series finds great variety in a limited number of themes. Like the other works in this set, it's dedicated to the cello-playing King Frederick Wilhelm II of Prussia, although Haydn elects not to do anything unusual in the cello part. The Op. 50 is seen as a response to the six quartets Mozart dedicated to Haydn a couple of years earlier, although again Haydn hardly alters his usual style in this quartet, save in the greater weight of the Minuet's Trio.

The initial Allegro resists establishing its D major home key at the very beginning, but it does quickly lay out a six-note motif that serves as the foundation for the entire movement. The movement is monothematic, aside from transitional and contrasting passagework that hardly amount to secondary melodies; it moves a quick but amiable theme along over a very busy accompaniment. The development, more extended than was Haydn's earlier practice, makes particular use of that six-note motto.

The Poco adagio shifts into D minor, although its cautious, creeping-down-a-dark-corridor primary melody soon steps into the brightness of F major. The first section is essentially a study in how to ornament and complicate this theme. The central section modulates into D flat major, then modulates further in the course of developing the rapid notes accompanying the original theme into a full-fledged second subject. The third section essentially covers the same ground as the first.

The Minuet (Allegretto) has a rustic unevenness to its skipping main theme, which continually flirts with the minor mode and includes coy, quiet, teasing phrases that break the music's flow. The central Trio section is more reserved, and includes a repeated-note melody that seems an echo of material in the slow movement.

The finale, Allegro con spirito, is responsible for the quartet's nickname, "The Frog." This is a reference not to that part of the bow, but to the effect produced by the violin's technique of bariolage, whereby the same note alternates quickly on two adjacent strings. (The result here actually sounds more like a cricket than a frog.) The repeated-note idea is one that has been carried over from the central movements, but here the effect is wittier and flashier. Like the first movement, this finale essentially takes a monothematic sonata-allegro form with a central development section, but without the sudden changes of mood that marked the quartet's earlier portions.

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