One of the lengthy and technically demanding virtuoso fugues. Although the exact occasion of its composition is unknown, it is highly probable that Bach wrote it for his own performance. Its completion is attributed to the Leipzig period in the 1730s, but the original version is thought to have already been established around 1720 during the Weimar period. Both the Prelude and the Fugue employ a concerto-like style of writing.

Characteristic of the Prelude are the divisions marked by perfect or half cadences, and the repetition of various elements. Cadential formulas appear approximately every four measures, clearly delineating the phrases. Each phrase often consists of a motive including an anacrusis at the beginning, a triplet figuration, and eighth-note chords, with two phrases forming a pair. That is, in the second instance, the elements are repeated with upper and lower voices exchanged or combinations altered. What this signifies becomes clear in the first movement of the later arrangement, the Triple Concerto for String Ensemble, Flute, Violin, and Harpsichord (BWV 1044). The opening motive is the tutti section, or ritornello; the figurations and chords are the solo sections; the cadential formulas mark the switching points of solo instruments; and the repetitions are for the exchange of roles among the instruments. Furthermore, the brilliant arpeggiated chords played by both hands in the middle section also serve as an improvisatory part for the harpsichord. However, BWV 1044 is not a direct arrangement of BWV 894. It is also possible that another "original work" common to both pieces existed. Moreover, there is no definitive proof that the arrangement was made by Bach himself. Nevertheless, it remains true that elements of a concerto were already hidden within BWV 894.

This style of writing is consistent in the Fugue as well. In addition to the repetition of elements, changes in combinations, and voice exchanges, cadential formulas involving all voices simultaneously are frequently observed, making it sound more like a second Prelude than a Fugue. The contrapuntal techniques employed are not overly complex, but they make extensive use of inversions of each element, ascending and descending simultaneously to reach low and high registers, or having both hands approach and separate to utilize a wide range. This piece was arranged as the final movement in the Triple Concerto, BWV 1044. At that time, the triplets appear only in the harpsichord part, while the flute and violin are given a leisurely 4/4 motive consisting of the first note of the triplets. Here, the extreme contrast between the harpsichord and the other instruments comes to the forefront, and the original form of the Fugue as a contrapuntal piece is almost no longer discernible; moreover, entirely non-fugal sections were newly added in the middle.