The constituents of the internal structure of words are called morphemes in Turkic. Morphemes that have a meaning on their own are referred as roots while morphemes that do not have a stand-alone meaning but have function related to meaning or conjugation only when combined with the root are called suffixes. Since roots are morphemes that being subjected to, they typically do not undergo any change. Beside this, suffixes are dependant morphemes, they become varied and multi-shaped to fit the root However, some suffixes are observed to change the base they are added. Suffixes that causes a change in the base they attach to are categorized as dominant suffixes. For example, alkış (< alka-ş), küsüş (< küse-ş), ülüş (< üle-ş) etc. In Altun Yaruk, one of the Uyghur works, there are 3641 entries, and 2414 of these are derivative words. With this feature, it is one of the few rich and important texts of the Uyghur period. Therefore, the results of the studies on Altun Yaruk will also apply to Old Turkic as well as Uyghur. In this article, the dominant derivational suffixes in Altun Yaruk have been identified, in what type of words these suffixes cause ch

Dominant suffix, morphology, Altun Yaruk, old Turkic.