Abstract
In this paper, the origin of Turkic derivational suffixes is discussed. It was noted that there are various approaches to this case, one of them being the theory of grammaticalization which suggests that Turkic derivational suffixes come from content words, while the other being based on the one-sound morphemic elements that are common to some derivational suffixes. The main one-sound formants in the language of Orkhon Inscriptions that we investigate are the elements -l, -g, and -m. The element -l occurs both in denominal and deverbal words, whereas the formants -g and -m are registered mostly in deverbal nominal words.