The present paper focuses on the acquisition and the use of Hungarian inflectional morphology by children. The aim of this paper is to show how inflectional affixes are embedded in the knowledge of children and what are the problematic parts that are acquired only in a later language learning stage. Specifically, the aim of the experiment discussed in this paper is to examine how adultlike and non-adultlike inflectional forms are created by children, using the accusative suffix.