The Latin rhythmic hexameter or accentual hexameter is a kind of Latin dactylic hexameter which arose in the Middle Ages alongside the metrical kind. The rhythmic hexameter did not scan correctly according to the rules of classical prosody; instead it imitated the approximate sound of a typical metrical hexameter by having roughly the same number of syllables and putting word accents in approximately the same places in the line.

The rhythmic hexameter flourished between the 3rd and 9th century A.D. The earliest examples come from what is now Tunisia in north Africa. One poet to use it for literary compositions was Commodian, who is thought to have lived in North Africa in the 3rd century A.D. Other examples come from Portugal, Spain, Lombardy in northern Italy, and southern France. Several examples are found on tombstones, but there is also an anonymous Christian work of the 6th or 7th century called Exhortatio poenitendi, and a book of riddles of the 8th century.

Over the centuries the style of the rhythmic hexameter underwent various changes; for example, in some early versions it had six stresses in each line, whereas later it had five. It has been suggested by one scholar that in its later form, with its five stresses with a caesura between the second and third, it eventually developed in France into the early form of iambic pentameter.

One of the first scholars to make the distinction between rhythmic and metrical poetry was the English monk Bede in his book On Metre. Basing his definition of rhythm on an earlier one by Marius Victorinus, he defines rhythm as "the composition of words modulated not by metrical quantity but by the number of syllables according to the judgement of the ears".

It seems that not all rhythmic poems were made with equal skill. Bede observes that common people make rhythmic poems "in a rustic way" (rustice), but learned people "in a learned way" (docte). He cites as a good example of a rhythmic poem imitating the iambic metre the hymn O rex aeterne, Domine, and of the trochaic the hymn Apparebit repentina dies magna Domini.

With iambic and trochaic metres, the word accents in the rhythmic style tend to follow the ictus of the metre. However, with a dactylic hexameter, except in the last two feet, where metre and accent coincide, this is not the case, and the accent does not usually coincide with the beginning of a foot. A rhythmic hexameter, therefore, generally has the last two accents fixed, but the earlier ones variable, the first accent occurring sometimes on the 1st, sometimes on the 2nd, 3rd, or even 4th syllable.

A typical metrical hexameter is made up of six feet, each of which can be either a dactyl (– u u) or a spondee (– –), the last two feet almost always being dactyl + spondee (– u u | – x) (the final syllable can be long or short). Thus the general scheme or pattern is:

There is a usually a break, called a caesura, in the middle of the 3rd foot. Thus a typical line might be: