In this article the author investigates the functions of three case forms. Traditionally, Indo-Europeans and turkologists, following E. Kurilovich called these forms are «grammatical». We are talking about nominative, genitive and accusative cases. As you know, Russian and Turkic languages belong to different morphological types - Russian is a inflectional language, all Turkic languages are agglutinative languages. Typological differences in them are manifested not only at the level of morpheme addition, but also in all language tiers. It can be traced that in the Turkic languages the order of occurrence of case forms is opposite to that which we find in the Russian language. The author, based on the analysis proposed by G.P. Melnikov, puts forward a hypothesis explaining this state of affairs.