The hysteron proteron (from the Greek: ὕστερον πρότερον, hýsteron próteron, "later earlier") is a rhetorical device. It occurs when the first key word of the idea refers to something that happens temporally later than the second key word. The goal is to call attention to the more important idea by placing it first.

The standard example comes from the Aeneid of Virgil: "Moriamur, et in media arma ruamus" ("Let us die, and charge into the thick of the fight"; ii. 353). An example of hysteron proteron encountered in everyday life is the common reference to putting on one's "shoes and socks", rather than "socks and shoes".

By this deliberate reversal, hysteron proteron draws attention to the important point, so giving it primacy. Hysteron proteron is a form of hyperbaton, which describes general rearrangements of the sentence.

It can also be defined as a figure of speech consisting of the reversal of a natural or rational order (as in "then came the thunder and the lightning").