The article offers to the classification of the declination system in the grammatics of Antic period. There are given theories of the great thinkers of Antic period, including opinions of Aristotle, Chrisipus, Diogenes, Amonius, Aristophane of Byzantium, Donatianus, Aristarchus, Herodian and Dionysius of Thrax. Unfortunately, there's too little information about the declination system in the grammatics of Antic period. In the details we can talk about the case system according to the Grammar of Dionysius of Thrax Tεχνη γραμματικη (Art of grammar).On the basis of considered grammatics we can state that in the grammatics of Antic period there is no inforamtion about the declination system and its types, but there's the tendency of systematization of noun flexion by the cases.

In the article there's also given the origin of the terms πτωσις and κλíσις. At the beginning they are used in the different broad sense, than they have today. Thus, according to Aristotle πτωσις means all forms of the word that is derived from the "normal" (initial) form and it offers almost to all parts of speech, while the term κλíσις means not only the declination, but commonly the inflexion of the world (both: declination and conjugation).

The modern meaning of the term πτωσις was given by Stoics. As for the term κλíσις, in the modern Greek language it has preserved its meaning and is used both for the declination, and for the conjugation.